NOAATECHNICALMEMORANDUMCORALREEFCONSERVATIONPROGRAM(CRCP)4

NOAATECHNICALMEMORANDUMNOSNCCOS56

Coral Disease and Health Workshop: 

Coral Histopathology II 

SB Galloway, CM Woodley, SM McLaughlin 

NOAA/NOS/NCCOS 

Center for Coastal Environmental Health and Biomolecular Research 

TM Work, VS Bochsler, CU Meteyer, L Sileo 

US Geological Survey, National Wildlife Health Center 

EC Peters 

Tetra Tech, Inc. 

E Kramarsky-Winters 

Tel Aviv University, Department of Zoology 

JF Morado 

NOAA/NMFS/Alaska Fisheries Science Center 

PG Parnell 

Clemson Veterinary Diagnostic Center 

DS Rotstein 

University of Tennessee, College of Veterinary Medicine

RA Harley, J Nicholson 

MUSC, Department of Pathology and Laboratory Medicine 

TL Reynolds 

Johns Hopkins University, Department of Pathobiology 

NOAA Technical Memorandum NOS NCCOS 56 and CRCP 4 

December 2006 

United States Department National Oceanic and National Ocean Service 

 of Commerce Atmospheric Administration 

Carlos M. Gutierrez Conrad C. Lautenbacher, Jr. John (Jack) H. Dunnigan 

Secretary Administrator Assistant Administrator 
ii 

About This Document 

Editors’ Acknowledgements: This document was prepared and printed 

with support from the National Oceanic and Atmospheric Administration 

(NOAA) through the Coral Reef Conservation Program (CRCP). Layout 

and design was provided by Thierry Work, US Geological Survey (USGS), 

Sylvia Galloway and Cheryl Woodley, NOAA/National Centers for Coastal 

Ocean Science/Center for Coastal Environmental Health and Biomolecular 

Research (NOAA/NCCOS/CCEHBR). The text was prepared and edited by 

the Workshop Participants, with final production edits provided by Sylvia 

Galloway.

Photo Credits: 

Images of coral specimens were provided by: Thierry Work, Kathy Price, Dana 

Williams, Molly Billmyre, Ernesto Weil, Debbie Santavy, Andy Bruckner, Esther Peters 

and Robert Jonas. 

Photomicrographs were captured, by the Workshop Participants during the group 

discussions, from histological slides provided by Shawn McLaughlin from NOAA’s 

International Registry of Coral Pathology (IRCP) collection. 

Meeting photographs were provided by: James Nicholson and Sylvia Galloway. 

Cover Design: James Nicholson, Medical University of South Carolina, Department of 

Pathology and Laboratory Medicine 

Coral Illustrations: Jennifer Clark, Jennifer Clark Scientific Illustrations 

Workshop Group Photo: James Nicholson, Medical University of South Carolina, 

Department of Pathology and Laboratory Medicine

Citation – 

Please cite this report as follows: 

Galloway SB, Work TM, Bochsler VS, Harley RA, Kramarsky-Winters E, 

McLaughlin SM, Meteyer CU, Morado JF, Nicholson JH, Parnell PG, 

Peters EC, Reynolds TL, Rotstein DS, Sileo L, and Woodley CM. 

2007. Coral Disease and Health Workshop: Coral Histopathology II. 

NOAA Technical Memorandum NOS NCCOS 56 and NOAA 

Technical Memorandum CRCP 4. National Oceanic and Atmospheric 

Administration, Silver Spring, MD. 84p. 
iii

CORAL DISEASE AND HEALTH WORKSHOP: 

CORAL HISTOPATHOLOGY II 

TABLE OF CONTENTS 

EXECUTIVE SUMMARY .......................................................................... 1

GOAL............................................................................................................. 2

PREFACE...................................................................................................... 3

INTRODUCTION ........................................................................................ 7

STUDY SETS....................................................................................................7 

ANATOMY OF CORALS..................................................................................8 

 FIGURE LEGENDS..................................................................................... 10

HISTOPATHOLOGICAL EXAMINATION.......................................................20 

RECOMMENDED FORMAT ...........................................................................21 

CONSENSUS HISTOPATHOLOGY DESCRIPTIONS ....................... 22

Slide 1.............................................................................................................22 

Slide 2.............................................................................................................24 

Slide 3.............................................................................................................26 

Slide 4.............................................................................................................28 

Slide 5.............................................................................................................30 

Slide 6.............................................................................................................32 

Slide 7.............................................................................................................34 

Slide 8.............................................................................................................36 

Slide 9.............................................................................................................38 

Slide 10...........................................................................................................40 

Slide 11...........................................................................................................42 

Slide 12...........................................................................................................44 

Slide 13...........................................................................................................46 

Slide 14...........................................................................................................48 

Slide 15...........................................................................................................50 

SUMMARY ................................................................................................. 52
iv 

RECOMMENDATIONS............................................................................ 54

ACKNOWLEDGEMENTS ....................................................................... 55

GLOSSARY................................................................................................. 57

REFERENCES............................................................................................ 77

AGENDA ..................................................................................................... 80

WORKSHOP PARTICIPANTS ............................................................... 82
1

EXECUTIVE SUMMARY 

The health and continued existence of coral reef ecosystems are threatened by an 

increasing array of environmental and anthropogenic impacts. Coral disease is one of 

the prominent causes of increased mortality among reefs globally, particularly in the 

Caribbean. Although over 40 different coral diseases and syndromes have been reported 

worldwide, only a few etiological agents have been confirmed; most pathogens remain 

unknown and the dynamics of disease transmission, pathogenicity and mortality are not 

understood. Causal relationships have been documented for only a few of the coral 

diseases, while new syndromes continue to emerge. Extensive field observations by coral 

biologists have provided substantial documentation of a plethora of new pathologies, but 

our understanding, however, has been limited to descriptions of gross lesions with names 

reflecting these observations (e.g., black band, white band, dark spot). To determine 

etiology, we must equip coral diseases scientists with basic biomedical knowledge and 

specialized training in areas such as histology, cell biology and pathology. Only through 

combining descriptive science with mechanistic science and employing the synthesis 

epizootiology provides will we be able to gain insight into causation and become 

equipped to handle the pending crisis. 

One of the critical challenges faced by coral disease researchers is to establish a 

framework to systematically study coral pathologies drawing from the field of diagnostic 

medicine and pathology and using generally accepted nomenclature. This process began 

in April 2004, with a workshop titled Coral Disease and Health Workshop: Developing 

Diagnostic Criteria co-convened by the Coral Disease and Health Consortium (CDHC), a 

working group organized under the auspices of the U.S. Coral Reef Task Force, and the 

International Registry for Coral Pathology (IRCP). The workshop was hosted by the U.S. 

Geological Survey, National Wildlife Health Center (NWHC) in Madison, Wisconsin and 

was focused on gross morphology and disease signs observed in the field. A resounding 

recommendation from the histopathologists participating in the workshop was the urgent 

need to develop diagnostic criteria that are suitable to move from gross observations to 

morphological diagnoses based on evaluation of microscopic anatomy. 

As a continuation of building the foundation and framework for coral disease diagnostics, 

the CDHC convened the Coral Disease and Health Workshop: Coral Histopathology II

in Charleston, South Carolina, July 11-14, 2005. The workshop was hosted by the 

Department of Pathology and Laboratory Medicine at the Medical University of South 

Carolina, Charleston, SC which provided expertise, facilities and equipment in support of 

the workshop. All of the histological slides and related photographs used in the 

discussions were prepared and supplied by the IRCP. This workshop brought together 15 

experts in veterinary and medical pathology and coral biology from national and 

international research institutes and government laboratories. The mission was to devise a 

standardized approach to examining microscopic anatomy and pathology of corals and a 

standardized nomenclature to facilitate accurate descriptions of the microscopic 

morphology of corals and enhance communication among specialists investigating causes 

of coral death. 
2 

The participants of this workshop deliberated for 3 days to refine the nomenclature for 

gross and microscopic anatomy of corals and systematically described microscopic 

changes associated with selected coral diseases. The findings and recommendations from 

the deliberations will be submitted to the research community for peer review. The 

standardized nomenclature and descriptions produced at this workshop will ultimately be 

made available to the scientific community through a variety of media including the 

World Wide Web. 

An exciting highlight of this meeting was provided by Professor Robert Ogilvie (MUSC 

Department of Cell Biology and Anatomy) when he introduced participants to a new 

digital technology that is revolutionizing histology and histopathology in the medical 

field. The Virtual Slide technology creates digital images of histological tissue sections 

by computer scanning actual slides in high definition and storing the images for retrieval 

and viewing. Virtual slides now allow any investigator with access to a computer and the 

web to view, search, annotate and comment on the same tissue sections in real time. 

Medical and veterinary slide libraries across the country are being converted into virtual 

slides to enhance biomedical education, research and diagnosis. The coral health and 

disease researchers at this workshop deem virtual slides as a significant way to increase 

capabilities in coral histology and a means for pathology consultations on coral disease 

cases on a global scale. 

GOAL: Set an internationally recognized standard for the description of coral 

microscopic anatomy and pathology.

SPECIFIC OBJECTIVES: 

• Refine nomenclature of gross and 

microscopic anatomy. 

• Describe microscopic changes 

associated with selected diseases. 

• Develop diagnostic criteria for 

coral conditions for a web-based 

learning tool for coral histology 

and histopathology. 

• Set internationally recognized 

standards for the description of 

coral histology. 

• Standardize terminology for the 

description of microscopic 

lesions of corals. 

• Develop morphological 

diagnoses for the histopathology 

of lesions from selected coral 

syndromes. 

Dr. Lou Sileo, facilitator of the July coral 

histopathology workshop. (Photo: Jim Nicholson) 
3

PREFACE 

Pathology is the study of the cause of disease and the modifications to cellular structure 

and function resulting from a diseased state. Diagnostic techniques such as histology, 

electron microscopy, immunocytochemistry and molecular pathology are powerful 

technologies for detecting such changes, but they have not been rigorously applied to 

coral disease investigations. The CDHC is organizing a series of workshops to focus on 

coral pathobiology to provide a forum for translating advances in biomedical and 

veterinary sciences, pathology, toxicology, and biotechnology to the study of coral 

disease and health. The cross-disciplinary nature of these workshops serves to provide 

the means by which coral disease researchers can interface with the mainstream 

biomedical community and allow more rapid progress in understanding the causes of 

coral disease and devising appropriate strategies for disease management. 

The first workshop in this series, ‘Coral 

Disease and Health Workshop: 

Developing Diagnostic Criteria’ held in 

2004, focused on gross morphology and 

disease signs observed in the field. During 

deliberations, problems with inconsistent 

data collection and the lack of objective 

criteria to describe cellular changes 

associated with disease at the microscopic 

level (histopathology) were identified as 

major impediments. Furthermore, routine 

use of the principles and practices of 

epizootiology and pathology of corals are 

just beginning. Confusion and uncertainty 

as to how cellular changes in these 

organisms should be described are evident 

in the literature. The second Coral 

Histopathology Workshop, reported here, 

was convened to address this issue. The 

workshop involved coral biologists and pathologists from various institutions to refine 

nomenclature of gross and microscopic anatomy and to systematically describe 

microscopic changes associated with selected diseases. 

Tissue sloughing in Acropora prolifera

observed in the Dry Tortugas, USA (Photo: 

Dana Williams) 

Presumed white band disease observed 

on Acropora palmata in Puerto Rico. 

(Photo: Andy Bruckner) 
4 

To date most field 

diagnoses have been 

descriptive in nature, 

failing to use traditional 

histopathological criteria. 

The workshop was 

organized around the 

review of histological 

slide sets from coral 

lesions associated with a 

variety of field diagnosed 

diseases. The workshop 

participants agreed to 

review a set of known coral lesions as a group and to develop a set of histopathological 

terms applicable to the description of these lesions. They also agreed to review 

independently unidentified histology slides containing coral lesions, followed by a group 

discussion of their independent observations, and to reach a consensus morphological 

diagnosis for the unknowns. 

The work of the group was greatly facilitated 

by the logistical support and expertise 

provided by MUSC’s Department of 

Pathology and Laboratory Medicine. The 

group had microscopes allowing pathologists 

to independently review slides, and a 

projection microscope for the group 

discussions. In addition photographs were 

captured from specific regions of each 

reviewed histological slide that illustrated 

the morphological diagnosis ascertained by 

the group. 

Finally, the workshop participants were given 

the opportunity to view and use the latest in 

histopathology technology1

, Virtual Slides2. 

An Aperio Virtual Slide Viewer3 was demonstrated during the first day of the workshop. 

 

1

 Disclaimer: This publication does not constitute an endorsement of any commercial product or intend to 

be an opinion beyond scientific or other results obtained by the National Oceanic and Atmospheric 

Administration (NOAA). No reference shall be made to NOAA, or this publication furnished by NOAA, in 

any advertising or sales promotion which would indicate or imply that NOAA recommends or endorses any 

proprietary product mentioned herein, or which has as its purpose an interest to cause directly or indirectly 

the advertised product to be used or purchased because of this publication. 

2

 Advances in Pathology, Microscopy & Molecular Morphology edited by Jiang Gu and Gerhard W. 

Hacker: ‘Virtual Microscopy and Virtual Slides in Teaching, Diagnosis, and Research’ by Jiang Gu and 

Robert W. Ogilvie; CRC, Taylor & Francis, Boca Raton, London, New York, Singapore, 2005, 356p. 

3

 http://www.aperio.com/ 

Workshop participants reviewing a photomicrograph. 

(Photo: Jim Nicholson) 

Debra Hazen-Martin, Jim Nicholson and Bob 

Ogilvie of MUSC. (Photo: Jim Nicholson) 
5

Aperio Representative demonstrating Virtual Slides to 

Bob Ogilvie (Photo: Jim Nicholson) 

Representative sections from each coral lesion under review were digitized using this 

system. These images were provided to each participant on a DVD for future viewing. 

Aperio viewing software is available (and downloadable) free from their website. The 

virtual slide viewer provides the same quality image, resolution, and magnifications that a 

user would get with a microscope. The scanner contains 80 micro lenses and has a 24 

mega-pixel capability. A unique feature of the software associated with the scanner is the 

ability to conference and view slides jointly over the internet, with control of slide 

movement and focus available (permission granted by scanner operator) to each 

participant of the conference. It was agreed that this technology would be extremely 

useful to share information on histopathology among colleagues interested in coral 

disease diagnosis and as a teaching tool. 
6 
7

INTRODUCTION 

The prevalence and severity of reef degradation due to coral disease has increased 

considerably over the last two decades. Emerging coral diseases have been linked to 

biotic and abiotic stressors and their synergistic interactions. Coral disease research is in 

its infancy and only beginning to take advantage of technologies and methodologies 

routinely used in epizootiology, clinical and diagnostic medicine, and pathology. This 

Coral Histopathology Workshop (and its predecessor) provided forums to begin adapting 

advances in biomedical and veterinary sciences, pathology, toxicology, and 

biotechnology to the study of coral disease and health; it also provided a foundation on 

which to build a framework for coral disease research that can interface with mainstream 

medical and veterinary research. The goals of this Workshop were to produce standards 

for (1) morphological descriptors based on accepted medical terminology, (2) consistent 

and concise descriptions of lesions in the field, as well as (3) clinical morphological 

diagnoses in the laboratory. Consensus reached during this workshop will be peer 

reviewed by the coral scientific community, both in public settings where the materials 

will be presented in workshop/discussion formats, directly soliciting review by others 

establishing terminology for the field, and through opinion papers in the peer-review 

literature to adopt specialized terminologies to facilitate communication among 

histopathologists. Once adopted, the terminology and microscopic descriptions will 

enable development of 

instructional materials and 

distance learning tools for coral 

histopathology. 

STUDY SETS OF 

HISTOLOGY SLIDES 

PROVIDED BY THE IRCP 

An important facet of this 

workshop was the use of study 

sets of slides with serial sections 

from the same sample for 

independent individual microscopic review. Study sets for the 

workshop were provided by the 

International Registry of Coral 

Pathology at the NOAA/NOS/NCCOS/CCEHBR Cooperative Oxford Laboratory (COL) 

in Oxford, MD. Microslides were prepared from coral tissues accessioned by IRCP, from 

paraffin blocks provided by individual investigators, and the Registry of Tumors in 

Lower Animals (RTLA) in Sterling, VA. Contributors included Andy Bruckner, 

Margaret Miller, Esther Peters, Caroline Rogers, Debbie Santavy, Lou Sileo, Ernesto 

Weil, Dana Williams, Thierry Work, and Cheryl Woodley. COL staff who contributed to 

the preparation of the study sets included Kathy Price, Molly Billmyre, Dorothy Howard, 

Bob Bingaman and Shawn McLaughlin. 

E. Peters discusses coral pathology with R. Harley, T. 

Reynolds and V. Boschler. (Photo: Sylvia Galloway) 
8 

ANATOMY OF CORALS 

(Note: Terms relevant to the description of coral histology are shown in blue at 

their first mention in the text, and are linked to the Glossary) 

Gross anatomy of a scleractinian polyp from an imperforate coral (Fig. 1a) 

Colonial scleractinian corals are composed of numerous interconnected polyps. The 

coenenchyme is the tissue between polyps and consists of a tubular network of 

gastrovascular canals that connect the gastrovascular cavity (gastric cavity) of adjacent 

polyps. At the oral end of the polyp are tentacles surrounding the oral disk; they have a 

bulbous structure at their tips, the acrosphere. The tentacles are studded with 

nematocysts/spirocysts, either scattered or clustered. Inside the ring of tentacles, within 

the oral disk, is a structure that surrounds the mouth and may be elevated, the peristome. 

Below the mouth is an invagination of the epidermis to form a short muscular tubular 

passageway to the gastric cavity, the actinopharynx. The area comprising the oral disk 

and actinopharynx is the column. The lower portion from the actinopharynx to the aboral

end of the polyp is the coenosteum. Polyps and interconnecting tissues alike are made up 

of the same tissue layers. The surface body wall contains epidermis, mesoglea, 

gastrodermis and is found in the polyp and coenenchyme. The actinopharynx body wall 

lines the lumen of the actinopharynx. The basal body wall is the tissue apposed to 

skeleton, consists of calicodermis and gastrodermis separated by mesoglea, and is found 

in the aboral region of the polyp and lining the gastrovascular canals. Within the 

gastrovascular cavity are mesenteries, that provide structural support and increase the 

surface area of the gastrodermis to improve nutrient absorption, and the gonads develop 

within these structures. 

Gross anatomy of a gorgonian polyp (Fig. 1b) 

Colonial gorgonian polyps have some similarities in structure to scleractinian polyps but 

differ in significant aspects. The oral (distal) portion of the polyp, bearing the mouth and 

tentacles, is the anthocodia. Gorgonian polyp tentacles are characterized by two 

diametrically arrayed rows of short pinnules. The polyps are anchored to the axis at their 

aboral end and in some species the polyp is surrounded by a rigid structure, the 

anthostele, into which the anthocodia may be withdrawn. The axis has a central chord

and is surrounded by an axial cortex and sheath. The axial sheath contains longitudinal 

canals characterized by sclerites that differ from those found in the coenenchyme. The 

coenenchyme is the tissue continuous between polyps, consisting of the surface body 

wall, gastrovascular canals and solenia, penetrating through the thick mesoglea stiffened 

with sclerites. 

Skeletal features of a noncolonial scleractinian coral (Fig. 1c) 

The skeleton deposited by an individual polyp within a colony is the corallite. The 

corallite is defined by three regions, the calice the columella, and the theca. The columnshaped skeletal projection of the central basal plate or modified inner septal edges is the 

columella. The calice includes the upper oral surface of a corallite, while the theca is the 

wall of the skeletal cup (corallite). The septa, vertical calcareous partitions, radiate from 

the corallite wall toward the central axis within the calice and provide support to the 

mesenteries. Extensions of the septa outside the calice onto the coenosteum are the costa. 
9

Skeletal features of colonial scleractinians (Fig. 2) 

The coral skeleton may be porous (perforate), with connections between the polyps 

through the skeleton (Fig. 2a-b), or nonporous (imperforate) (Fig. 2c-d).

Mesentery features of a scleractinian polyp (Fig. 3) 

Mesenteries are internal longitudinal partitions of tissue that provide structural support 

and increase surface area within the gastrovascular cavity. They are important in 

nutritional functions as well as fertility of anthozoans. A mesentery develops by 

infolding of the mesoglea and its lining gastrodermis from the body wall of the polyp. 

Multiple mesenteries are arranged radially within the gastrovascular cavity of the polyp 

(between the septa in scleractinian corals) and are attached to the oral disk. In the oral 

region, mesogleal pleats supporting the longitudinal retractor muscles are prominent; in 

the aboral region, gonads and loops of the mesenterial filament develop. Complete 

mesenteries attach to the polyp wall whereas incomplete mesenteries float free within the 

lumen of gastrovascular canals. The free edge of mesenteries consists of a cnidoglandular 

band with adjacent lobes. 

Surface body wall organization of a scleractinian polyp; cell types associated with 

the epidermis, mesoglea, and gastrodermis (Fig. 4)

The generic cellular organization of coral tissue layers consists of an epidermis, the 

mesoglea and a gastrodermis. The epidermis may be either, located next to the external 

environment (surface body wall), located next to the skeleton (basal body wall) or located 

in the actinopharynx (actinopharynx body wall). The epidermis contains numerous cells 

including cnidae, mucocytes (mucosecretory cells), pigment cells, calicoblastic cells, 

epitheliomuscular cells and other supporting cells. The calicoblastic epithelium

(calicodermis) is apposed to and secretes the calcium carbonate, aragonite, skeleton. The 

epidermis of the actinopharynx has more supporting cells than the surface body wall 

epidermis, with notably elongated cilia, that function to move food particles and fluid 

into and out of the gastrovascular cavity. The mesoglea is a homogenous connective 

tissue layer of variable thickness that may contain isolated cells. It is bordered either by 

epidermis and gastrodermis or by gastrodermis on both sides (as occurs in the mesentery, 

Fig. 3). The gastrodermis lines the digestive lumen, underlies the mesoglea, and contains 

zooxanthellae, or symbiotic algae, in membrane bound vacuoles. The gastrodermis may 

contain ciliated or flagellated support cells, cnidocytes, amoebocytes, sensory cells, 

mucocytes, granular gland cells and pigment cells. Neurons and epitheliomuscular cells 

are found in both epidermis and gastrodermis. The base of an epitheliomuscular cell 

contains a contractile portion within the plasma membrane, the myoneme, which attaches 

to the nucleus-containing portion of the cell by a peduncle and also attaches the cell to the 

mesoglea. 
10 

FIGURE LEGENDS FOR FIGURES 1-4. 

Figure 1a. Gross anatomy of a scleractinian polyp from an imperforate coral. 

Figure 1b. Gross anatomy of a gorgonian polyp. 

Figure 1c. Diagram of skeletal features of a noncolonial scleractinian coral. Only 

those skeletal features included in the glossary are labeled. Additional features 

important in scleractinian taxonomy are not labeled here. 

Figure 2a. Left, sagittal section through Acropora polyps, a perforate coral. Tissue 

fixed in Helly’s solution and stained with azocarmine G. Below, tissue section from 

a different Acropora sample, stained with hematoxylin and eosin. 

Figure 2b. Oblique section through Acropora polyps. The plane of the section 

passes through both oral (actinopharynx) and aboral (gonad) portions of polyps. 

Figure 2c. Left, sagittal section through Montastraea polyps, an imperforate coral. 

Tissue fixed in Z-Fix solution and stained with azocarmine G. Below, tissue section 

from a different Montastraea sample, stained with hematoxylin and eosin. 

Figure 2d. Oblique section through a Montastraea polyp. The plane of the section 

is from the oral region of a contracted polyp. 

Figure 3. Three-dimensional diagram of the key features of a scleractinian polyp 

mesentery. In the oral region, mesogleal pleats supporting the longitudinal 

retractor muscles are prominent; in the aboral region, gonads and loops of the 

mesenterial filament develop. 

Figure 4. Three-dimensional diagram of the surface body wall of a scleractinian 

polyp, showing cell types of the epidermis, mesoglea, and, gastrodermis. 
Figure 1a. 
Figure 1b. 
Figure 1c. 
Figure 2a. 
Figure 2b. 
Figure 2c. 
Figure 2d. 
Figure 3. 
Figure 4. 
20 

HISTOPATHOLOGICAL EXAMINATION OF CORAL TISSUE 

Three regions and their accompanying structures and tissue types are examined: 

1. Coenenchyme 

a. Gastrovascular canals (surface and basal body walls) 

2. Polyp 

a. Oral 

tentacles (surface body wall) 

oral disk (surface body wall) 

peristome (surface body wall) 

actinopharynx (actinopharynx body wall)

b. Aboral 

body 

wall (surface and basal) 

mesenteries (complete or incomplete) 

proximal 

mesogleal pleats 

gonads 

filaments 

lobes 

cnidoglandular band 

gastric cavity 

3. Skeleton 

a. septa 

b. columella 

c. corallum 

d. basal plate 
21

RECOMMENDED FORMAT FOR DESCRIBING HISTOLOGY AND 

HISTOPATHOLOGY OF CORALS 

Signalment/History:

Specimen information (genus-species, common name, shape descriptors); 

Description of affected coral (color change, tissue loss, skeletal damage, 

growth anomaly, other descriptors); 

Sample information (identification number, healthy tissue, diseased tissue, 

other species, sediment/soil/sand, water); 

Reef descriptors (name, general location, type, depth, GPS coordinates);

Collection site data (water clarity, map, transect information, disturbance 

signs, photos, videos); 

Observer information (name, address, contact information, date of 

observation). 

Field Diagnosis: Complete description of the gross lesion and a preliminary 

diagnosis of the disease condition or suspected disease name. 

Histopathology Description: description given for each of three tissue areas. 

 Coenenchyme 

 Polyp 

 Skeleton 

Morphologic Diagnosis:

 Description of tissue lesions using consensus coral histopathology terms. 

Recommendations: specific sampling, sectioning, staining or amplification 

suggestions. 
22 

CONSENSUS HISTOPATHOLOGY DESCRIPTIONS

FOR SELECTED CORAL LESIONS 

Slide 1 

Signalment/History: Acropora palmata (IRCP 180-A2) collected from Lameshur Bay, US 

Virgin Islands on 15 July 2004 by Lou Sileo, Thierry Work and Caroline Rogers. 

Field Diagnosis: Presumed White Patch 

Histopathology Description (Fig. 6):

Coenenchyme: Viable tissue terminates abruptly and is characterized by full 

thickness tissue loss. A narrow edge of necrotic tissue precedes the termination 

(Fig. 6B, ↑). There is focal ulceration of the surface body wall characterized by 

ablation of epidermis and mesoglea and dissociation of gastrodermal cells with 

liberation of zooxanthellae some of which exhibit vacuolization of the cytoplasm. 

These vacuolated zooxanthellae are found within gastrovascular canals and are 

admixed with necrotic debris in the superficial peristome. There is multifocal to 

focally extensive vacuolization of gastrodermis which was more severe within the 

deep region. The epidermis is focally sloughed and vacuolated. No bacterial 

aggregates are seen. Aborally, there are scattered areas of necrotic gastrodermis 

occasionally associated with hyalinized mesoglea. 

Polyp: Within ova there is central clumping of eosinophilic granules (yolk); 

vacuolization of surrounding wall (Fig. 6C, ↑); presence of multiple round 

structures with basophilic stippling surrounded by a vacuole. Occasional 

filamentous structures infiltrate gastrodermis; there is no associated necrosis. 

Cnidoglandular bands are necrotic and characterized by pyknosis and dissociation

Figures 5 A & B. White patch lesions on Acropora palmata: A- field photo (Thierry Work); 

B- fixed specimen (Kathy Price). 

A B
23

of gastrodermal cells, of many proximal mesenteric filaments. Occasional 

spermaries are noted. 

Skeleton: Well within the portion denuded of tissue, there are abundant mixed 

populations/mats of endolithic organisms. 

Other, mucus: There are scattered clumps of eosinophilic debris and spirocysts

(Fig. 6A, ↑). 

Morphologic Diagnosis: None 

Recommendations:

• Gram stains for bacteria 

• GMS for fungi 

• Giemsa for suspect organisms in the tissues surrounding ova. 

• Trichrome or Aniline Blue for hyalinized mesoglea. 

 

Figure 6 A-D. Photomicrographs of diseased Acropora palmata tissue fixed in seawater:Z-Fix5 and 

stained with MHE6

 (A, B, C) and PAS/AB7 (D): A- 4x8, surface body wall showing eosinophilic 

debris and spirocysts in mucus layer (↑); B- 2x, surface body wall showing necrotic tissue preceding 

the termination (↑); C- 20x, showing ovum vacuolization of surrounding wall (↑); D- note fungal 

hyphae invading gastrodermis of basal body wall (↑). 

A 

C D 

B 
24 

Slide 2 

Signalment/History: Dichocoenia stokesii (IRCP 225) collected from Navassa Island, 

US National Wildlife Refuge, on November 2004.

Field Diagnosis: Presumed white plague. 

Histopathology Description (Fig. 8): 

Coenenchyme: Diffusely, in surface body wall, there are few zooxanthellae. 

Surface body wall diminishes progressively. There is abrupt termination of the 

epidermis and gradual diminution of the basal body wall. 

Polyp: Near the edge of the section, there is full thickness ablation of the surface 

body wall revealing underlying mesenteric filaments with necrotic gastrodermis 

characterized by dissociation of cells (Fig. 8A&B, ↑). Moderate numbers of 

coccidian oocysts are within lobes of mesenterial filaments (Fig. 8C, ↑). The 

apposition of these 2 layers at the edge of a lesion is indicative of the first stages 

of tissue repair (Fig. 8D, ↑). 

Skeleton: No remarkable lesions seen. 

Morphologic Diagnosis:

• Severe, focal, ablation associated with gastrodermal necrosis, surface body wall, 

and polyp. 

Recommendations:

• Conduct further characterization to investigate and better understand the process 

of tissue repair in corals.

• Conduct laser capture of the coccidian oocysts within the lobes of the mesenterial 

filaments in order to further identify.

Figures 7 A & B. White plague lesion on Dichocenis stokesii: A- field photo (Dana Williams); 

B- fixed specimen (Molly Billmyre). 

A B
25

5

 Anatech Ltd., Battle Creek Michigan. 

6

 MHE = Mayer’s Hematoxylin and Eosin (AFIP). 

7

 PAS/AB = Periodic Acid Schiff/Alcian Blue (AFIP) 8

 All magnifications provided for photomicrographs reflect the objective used, not that the image is 

magnified that many times 

Figure 8 A-D. Photomicrographs of diseased Dichocoenia stokesii tissue fixed in seawater:Z-Fix and 

stained with MHE: A- 4x, necrotic gastrodermis (↑); B- 20x enlargement of A showing necrotic 

gastrodermis (↑); C- 40x, Coccidia in mesenterial filaments (↑); D- apposed epidermis and gastrodermis 

(↑). 

A B 

C D 
26 

Slide 3 

Signalment/History: Acropora palmata (IRCP 206-3B) collected from Mona Island, 

Puerto Rico on 13 July 2004 by Andy Bruckner. 

Field Diagnosis: Presumed white band disease. 

Histopathology Description (Fig. 10):

Coenenchyme/Polyp: There are numerous nematodes (Fig. 10B) mixed with 

debris and fragments of laminar eosinophilic material (hyalinized mesoglea). 

Cellular debris with intact nuclei (2-3 μm) is present in the intestine of the 

nematodes. Surface body wall is dissociated and there is multi-focal loss of 

epidermis. Zooxanthellae appear pale and vacuolated. There is multifocal 

necrosis of gastrodermis characterized by cytoplasmic fragmentation, pyknosis, 

karyorrhexis and liberation of zooxanthellae with swelling of mesoglea (Fig. 10A, 

↑). Accumulations of cellular debris are present in the lumen of the 

gastrovascular canals. 

Polyp: Epidermal nematocysts are infrequent. There is segmental loss of 

mesoglea. 

Skeleton: No remarkable lesions are seen. 

Morphological Diagnosis:

• Mild multifocal necrosis in the gastrodermis of the coenenchyme and polyps.

Recommendation: Obtain larger section of coral tissue for examination. 

Figure 9 A & B. Presumed white band disease observed on Acropora palmata: A- field 

photo (Andy Bruckner); B- fixed specimen (Kathy Price). 

A B
27

Figure 10. A. Photomicrograph of diseased Acropora palmata tissue fixed in Helly’s and 

stained with MHE: 4x, note swelling of mesoglea (↑); B. Nematodes in A. palmata tissue; 

undetermined whether they are scavenging or are involved in the pathology. 

B 

A 
28 

Slide 4 

Signalment/History: Acropora prolifera (IRCP 110) collected from Dry Tortugas, 

Florida on 23 July 2003 by Dana Williams and Margaret Miller. 

Field Diagnosis: Presumed white band disease. 

Histopathology Description (Fig. 12):

Coenenchyme: Tissue terminates abruptly as evidenced by rare isolated nests of 

viable tissue within gastrovascular canals within denuded skeleton remote from 

contiguous tissue. Numerous aggregates of basophilic rods are within mesoglea. 

Zooxanthellae within gastrodermis of the surface body wall appear pale. Basal 

body wall epidermis is segmentally attenuated and full thickness surface body 

wall characterized by linear arrangement of gastrodermal cells with shrunken 

cytoplasm. Scattered arthropods are present, adjacent to terminus of tissues, 

significance unknown. 

Polyp: No remarkable lesions seen. 

Skeleton: No remarkable lesions seen. 

Morphologic Diagnosis: 

• Numerous bacterial aggregates within the mesoglea of the coenenchyme. 

• Moderate multifocal attenuation of the surface and basal body wall of the 

coenenchyme. 

Recommendation: None. 

Figure 11 A & B. Presumed white band disease observed in Acropora prolifera: A- field photo 

(Dana Williams); B- fixed specimen (Kathy Price). 

A B
29

Figure 12 A-F. Photomicrographs of diseased Acropora prolifera tissue fixed in seawater:Z-Fix and 

stained with MHE: A- 4x, remnant tissue; B- 10x, arthropods; C- 20x, bacterial aggregates (↑) in 

coenenchymal basal body wall (↑); D- 20x, surface body wall, zooxanthellae (↑); E- 40x, attenuation 

of coenenchymal basal body wall; F- 20x, arthropod (↑) in lumen of gastrovascular canal, bacterial 

aggregate in basal body wall. 

A B 

C D 

E F 
30 

Slide 5

Signalment/History: Siderastrea siderea (IRCP 156-B2) collected from Turrumote, 

Puerto Rico on 4 April 2004 by Ernesto Weil. 

Field Diagnosis: Presumed dark spots. 

Histopathology Description (Fig. 14): 

Coenenchyme: There is multifocal exfoliation of 20-30% of the surface body 

wall. This observation may be an artifact rather than a lesion (Fig. 14B&C, ↑). 

Free zooxanthellae and cell debris are within canals. Diffusely, variably sized 

large clear vacuoles distort all cell layers (normal for Siderastrea) (Fig. 14D, ↑). 

At interface between deep gastrovascular canals and skeleton, there are multifocal 

dense accumulations of pleomorphic bulbous thick walled nonseptate organisms 

with irregular walls (fungi) (Fig. 14E, ↑). In a separate area, there is an extracellular matrix with cellular debris necrosis intermixed with islands of viable 

tissue. 

Polyp: No remarkable lesions seen. 

Skeleton: No remarkable lesions seen. 

Other, Mucus: Sloughed cellular debris is entrapped within the mucus layer 

multifocally overlying regions of depressed coral tissue (Fig. 14A, ↑). 

Morphologic Diagnosis: 

• Severe multifocal full thickness tissue loss of the coenenchyme. 

• Endolithic mycosis. 

Recommendation: Prepare undecalcified sections for histopathologic preparation to 

examine the interaction of suspect fungi with tissue and skeleton. 

A 

Figure 13 A & B. Presumed dark spots observed in Siderastrea siderea: A- field photo 

(Ernesto Weil); B- fixed specimen (Kathy Price). 

B 
31

A B 

Figure 14 A-E. Photomicrographs of diseased 

Siderastrea siderea tissue fixed in seawater:Z-Fix 

and stained with MHE: A- 10x, sloughed debris (↑); 

B- 4x, fragmented surface body wall (↑); C- 10x 

magnification of B; D- 2x, clear vacuoles (↑); E- 20x, 

thick walled, nonseptate organisms at interface (↑). 

D 

E 

C 
32 

Slide 6 

Signalment/History: Montastraea annularis (EPA FLK9503B2) collected from Sand 

Key, Florida in March 1995 by Debbie Santavy.

Field Diagnosis: Presumed yellow blotch. 

Histopathology Description (Fig. 16): 

(Comment: The quality of preparation is poor.) 

Coenenchyme: Clumps of eosinophilic debris mixed with pyknotic nuclei are 

within the lumen of gastrovascular canals. This observation may be necrosis or 

autolysis, but was not determined. 

Polyp: Gastrodermis of some mesenterial filaments contains large numbers of 

eosinophilic granular cells. Multiple foci of gastrodermal cells are dissociating 

and sloughing into the lumen of gastrovascular canals (autolysis, Fig. 16C). 

Within the gastric cavity are accumulations of golden-brown granules. Within 

cnidoglandular bands are intracellular accumulations of golden-brown pigment 

(normal). 

Skeleton: There are clumps of golden-brown debris (Fig. 16A, ↑) adjacent to a 

loose mat of thick non-septate, irregular walled fungal hyphae (Fig. 16B, ↑). 

These appear to be in the skeleton. 

Morphologic Diagnosis: Undetermined.

Recommendation: None. 

Figure 15 A & A’. Presumed yellow blotch observed on Montastraea annularis: A- example of 

gross disease signs on an affected colony, field photo, A’- closeup example of lesion (Esther 

Peters); fixed specimen photo unavailable. 

A A’ 
33

Figure 16 A-C. Photomicrographs of diseased Montastraea annularis tissue fixed in 

Helly’s and stained with MHE: A- 10x, golden brown debris in the gastrovascular 

canal region that has lost its integrity (↑); B- 40x, loose mat of non-septate, irregular 

walled organisms within skeleton (↑); C- 20x, golden brown debris in the 

gastrovascular canal lumen (↑). 

A B 

C
34 

Slide 7

Signalment/History: Acropora palmata (RTLA 5091) collected from Tague Bay, US 

Virgin Islands on 28 July 1981 by Esther Peters. 

Field Diagnosis: Colony not showing disease, but located in the vicinity of colonies 

with external signs of presumed white band disease. 

Histopathology Description (Fig. 18): 

Coenenchyme: There is multifocal full thickness fragmentation of surface body 

wall on one end of the section accompanied by sloughing of gastrodermis. 

Multifocally, within deep basal body wall epithelia and surface body wall 

mesoglea is denuded (↑). Occasional bacterial aggregates (basophilic rods 

appearing eosinophilic) are within mesoglea of calicodermis. Zooxanthellae were 

diffusely interspersed in the gastrodermis, but this may suggest species variation. 

There are focally extensive areas where no zooxanthellae were seen in 

gastrodermis of surface body wall. There are free zooxanthellae within 

gastrovascular canals (►). 

Polyp: Cnidoglandular band cells are focally dissociated. Ova and spermaries 

were present. 

Skeleton: No remarkable lesions seen. 

Morphologic Diagnosis: 

• Moderate decrease of zooxanthellae in the gastrodermis of the coenenchyme. 

• Mild multifocal bacterial aggregates in the basal body wall of the coenenchyme. 

• Mild multifocal fragmentation of surface body wall of the coenenchyme. 

A 

Figure 17 A. Acropora palmata

exhibiting signs presumed to be white 

band disease (Esther Peters): both field 

and fixed specimen photos unavailable 

for this sample. 
35

• Mild multifocal loss of the surface body wall and calicodermis of the 

coenenchyme. 

• Mild focal dissociation of the cells in the cnidoglandular band of the polyp. 

Recommendation: None.

Figure 18. Photomicrograph of Acropora palmata tissue fixed in Helly’s and stained with 

MHE: A- 20x, showing denuded mesoglea (↑) and free zooxanthellae in the gastrovascular 

canals (►).

A 
36 

Slide 8 

Signalment/History: Montastraea faveolata (IRCP 144B) collected from Weimburg, 

Puerto Rico in April 2004 by Ernesto Weil. 

Field Diagnosis: Presumed white plague. 

Histopathology Description (Fig. 20): 

Coenenchyme: Clumps of gastrodermal cells are within the lumena of 

gastrovascular canals. Diffusely, zooxanthellae appear to have a granular 

eosinophilic cytoplasm, the pyrenoid body is often difficult to visualize, and 

tinctorial contrast is lacking (loss of viability). 

Polyp: Within one polyp, there is diffuse necrosis of gastrodermis characterized 

by small fragments of cytoplasm and nuclear debris free in the lumen 

accompanied by free zooxanthellae; this is more prevalent in the mesenteries but 

also found in surface body wall (Fig. 20B&C, ►). Within areas of sloughing 

gastrodermis, zooxanthellae appear to have a granular eosinophilic cytoplasm, the 

pyrenoid body is often difficult to visualize, and a tinctorial contrast is lacking 

(loss of viability). There is an unstructured fibrillar amphophilic mass that 

appears to be mesoglea and which is surrounded by extracellular zooxanthellae 

(Fig. 20C, ↑). Epidermis and gastrodermis is lost regionally adjacent to the mass. 

At the base there is segmental loss of calicodermis (Fig. 20D, ↑). There is a focus 

of amorphous eosinophilic debris with free zooxanthellae within a single 

cnidoglandular band. Spermaries noted. 

Skeleton: There are mats of mixed fine eosinophilic filaments and thick irregular 

septate amphophilic structures (endolithic organisms) (Fig. 20A, ↑). 

Other: At the periphery of the entire section, tissue lysis is suggestive of 

collection artifacts (↑). 

Morphologic Diagnosis: 

• Moderate, diffuse, necrosis, gastrodermis, mesentery and surface body wall, one 

polyp. Addendum: Upon review of the gross lesion, it appears that the lesion 

Figure 19 A & B. Presumed white plague observed on Montastraea faveolata: A- similar 

field photo (Robert Jonas); B- fixed specimen (Kathy Price).

A B 
37

described above as peripheral collection artifact was actually part of the gross 

margin of tissue loss (the grossly observed lesion). 

Amended Morphologic Diagnosis:

• Diffuse gastrodermal necrosis, circumferential polyps. 

Recommendation: Perform a silver stain for demonstration of fungi. 

Figure 20 A-E. Photomicrographs of diseased 

Montastraea faveolata tissue fixed in seawater:ZFix and stained with MHE: A- 4x, endolithic 

organisms (↑); B- 20x, necrosis of gastrodermis 

and denuded mesoglea (↑); C- 10x, necrosis of 

gastrodermis and denuded mesoglea (↑) and 

unstructured fibrillar amorphic mass (►); D- 10x, 

segmental loss of calicodermis (↑); E- 2.5x, 

sloughing of epithelium (↑). 

A B 

C D 

E 
38 

Slide 9 

Signalment/History: Acropora cytherea (USGS 15440-006B) collected from Johnston 

Atoll, Central Pacific on 30 March 2001 by Thierry Work. 

Field Diagnosis: Growth anomaly. 

Histopathology Description (Fig. 22): 

Coenenchyme: Multifocal, poorly demarcated, unencapsulated regions of 

proliferation of haphazardly folded calicodermis with decreased space separating 

them (increased soft tissue density relative to skeletal density) are present (Fig. 

22A, ↑). These regions are composed of well-differentiated gastrodermis and 

calicoblastic epithelium (+/- increased cell density) and fewer polyps. 

Gastrodermal cells within the regions of proliferation are cuboidal and welldifferentiated with round euchromatic nuclei and vacuolated cytoplasm. 

Calicoblastic epithelial cells are also well differentiated with euchromatic nuclei 

(Fig. 22B, ↑). Mitoses are not observed. This region is covered by surface body 

wall; multifocally, the gastrodermis has few to no zooxanthellae and the 

epidermis lacks mucocytes. Mesoglea in the deep calicodermis is focally 

denuded. 

Polyp: Within the regions of proliferation, there is general absence of polyps. 

Existing polyps are haphazardly arranged within the peripheral regions of the 

masses (Fig. 22C, ↑). 

Skeleton: No remarkable lesions seen.

Morphologic Diagnosis: 

• Multifocal extensive hyperplasia of gastrovascular canals with an absence of 

zooxanthellae in the coenenchyme: 

Figure 21 A. Malformed Acropora cytherea: 

A-field photo (Thierry Work); fixed specimen 

photo unavailable. 

A 
39

 chaotic arrangement of scant polyps and, 

 overlying surface body wall lacks mucocytes and spirocysts. 

Recommendation: Conduct immunohistochemical stains for calicoblastic epithelium. 

A 

Figure 22 A-D. Photomicrographs of diseased Acropora cytherea tissue fixed in Helly’s and 

stained with MHE: A- 10x, haphazardly folded basal body wall (↑); B- 10x, high density of welldifferentiated calicoblastic epithelial cells (↑); C- 4x, chaotic arrangement of polyps; D- 10x, 

showing metazoan organism (↑). 

B 

C D 

A 
40 

Slide 10 

Signalment/History: Siderastrea siderea (IRCP 97-1) collected from Maryland Shoals, 

Florida, on 15 July 2003 by Esther Peters. 

Field Diagnosis: Presumed dark spots. 

Histopathology Description (Fig. 24):

Polyp: There are two pieces of tissue on this histoslide. One was embedded so 

that the section is through the upper polyp region and there are nice cross-sections 

through the polyps above the oral disc, showing tentacular and septal covering 

tissues. There is no evidence of skeletal endolithic organisms in most of this 

piece. At one margin, there is one polyp that is cut through a slightly deeper 

plane on one side so that two mesenteries with oocytes are shown. Endolithic 

organisms are present in the septa adjacent to the gonad bearing mesenteries in 

this polyp (Fig. 24A, ↑). The other piece of tissue was embedded as a longitudinal 

section of polyps from the colony margin, which had appeared “dark” when 

collected. The lesion edge is colonized by mixed plants and animals (Fig. 24B, 

↑). There are few zooxanthellae within gastrodermis, and those present were 

often shrunken with pale granular cytoplasm with indistinct cell walls. Large 

variably sized vacuoles distort the epidermis and gastrodermis of surface body 

wall and gastrodermis of mesenteries (species variation). 

Coenenchyme: No remarkable lesions seen. 

Skeleton: The skeleton shows an increased density of endolithic organisms 

aborally. The calicoblastic epidermis adjacent to, and sometimes being touched 

by the endoliths, has swollen and vacuolated mucocytes and the contents of the 

acidophilic granulocytes are dispersed, or the epidermis is necrotic (Fig. 24A, ↑). 

Morphologic Diagnosis: 

• Severe diffuse degeneration of zooxanthellae. 

Figure 23 A & B. Siderastrea siderea observed with presumed dark spots disease: A- similar field 

photo (Esther Peters); B- fixed specimen (Kathy Price). 

A B 
41

• Endolithic mycosis. 

• Full thickness disruption of the basal body wall at the leading edge of the 

endolithic fungi. 

Recommendations: 

• Stain with PAS and GMS to identify fungi.

• Examine histology of dark spot in species other than Siderastrea.

• Perform TEM on zooxanthellae. 

C Figure 24 A-C. Photomicrographs of diseased 

Siderastrea siderea tissue fixed in seawater:Z-Fix 

and stained with MHE: A- 40x, high density of 

endolithic organisms with cell lysis and granules 

(↑); B- 10x, colonization of the lesion edge by 

epibionts (e.g., filamentous macroalgae and 

arthropods) (↑); C- 10x, endolithic organisms. 

A B 
42 

Slide 11 

Signalment/History: Gorgonia ventalina (IRCP 151-B2) collected from Turrumote, 

Puerto Rico on 4 April 2004 by Ernesto Weil. 

Field Diagnosis: Presumed aspergillosis. 

Histopathology Description (Fig. 26):

Polyp: No remarkable lesions are seen. 

Skeleton/coenenchyme: There are large clefts between tissue and gorgonin and 

within gorgonin. In some cases, fan-shaped clusters of thin branching nonstaining structures invade the edge of the gorgonin (Fig. 26A, ↑). Tissues 

adjoining the cleft are lined by a thin brown membrane (melanized gorgonin 

cortex) (Fig. 26A, ►). Gorgonin cortex is thickened and melanized surrounding 

empty clefts and infected regions of gorgonin. Multifocally, the edge of the 

cortex is frayed. Adjoining these clefts are numerous eosinophilic granular cells 

(Fig. 26B, ↑). Within solenia are aggregates of cellular debris (Fig. 26C, ↑). In 

some cases, within the clefts, are large non-parallel walled structures containing 

intralumenal pyriform bodies. Cyanobacteria and concatenated rods and algae are 

also seen. These are surrounded by homogenous eosinophilic material. 

Morphologic Diagnosis: 

•Granulocytic infiltration of the mesoglea associated with moderate multifocal intragorgonal fungi. 

Recommendation: None. 

Figure 25 A & B. Gorgonia ventalina observed 

with presumed Aspergillosis: A- field photo 

(similar lesion photo, Ernesto Weil); B- fixed 

specimen (Kathy Price). 

A B 
43

E 

Figure 26 A-F. Photomicrographs of diseased Gorgonia ventalina tissue fixed in seawater:Z-Fix and stained 

with MHE: A- showing non-staining structures (hyphae) (↑) and deposited melanin (yellowish area) with 

adjacent tiny granules (►); B- 20x, aggregates of eosinophilic granular cells (↑); C- accumulations of debris in 

the lumen of the solenia (↑); D- 10x, cross section of a planula (↑); E- 10x, note fan-shaped aggregation of 

fungal hyphae (↑); F- higher power view of fan-shaped invasion of fungal hyphae (↑). 

A B 

D 

F 

C 
44 

Slide 12 

Signalment/History: Montastraea faveolata (IRCP 154-B3) collected from Turrumote, 

Puerto Rico on 4 April 2004 by Ernesto Weil. 

Field Diagnosis: Presumed yellow blotch. 

Histopathology Description (Fig. 28):

Coenenchyme: Unremarkable. 

Polyp: Unremarkable. 

Skeleton: There are sparse mats of large filamentous irregular structures (Fig. 

28B). 

Morphologic diagnosis: No remarkable lesions. 

Recommendation: Reevaluate section. 

A 

Figure 27 A & B. Presumed yellow blotch observed in Montastraea faveolata: 

A- field photo (photo similar lesion, Ernesto Weil); B- fixed specimen (photo: Kathy Price). 

B 
45

Figure 28. Photomicrograph of Montastraea faveolata tissue fixed in seawater:Z-Fix; A10x, unusual cut of an otherwise normal sample; B- 20x, sparse mats of large filamentous 

structures.

A 

B 
46 

Slide 13 

Signalment/History: Acropora prolifera (IRCP 57) collected from Dry Tortugas, Florida 

on 5 June 2003 by Dana Williams and Margaret Miller. 

Field Diagnosis: Sloughing tissue, no obvious diagnosis. 

Histopathology Description (Fig. 30): 

Coenenchyme: Moderate numbers of aggregates of basophilic bacilli are within 

the mesoglea between calicodermis and gastrodermis of the basal body wall lining 

gastrovascular canals (Fig. 30A, ↑). Some of the aggregates are in a space 

surrounded by mesoglea. There is an abrupt termination of viable tissue (full 

thickness) on one edge (Fig. 30B, ↑). Associated with that abrupt termination are 

numerous crustaceans (Fig. 30B, ►) and occasional ciliates and diatoms. Ova 

and spermaries are absent. 

Polyp: No remarkable lesions are seen. 

Skeleton: No remarkable lesions are seen. 

Morphologic Diagnosis: 

• Multiple bacterial aggregates located within the mesoglea of the gastrodermis and 

basal body wall. 

• Focal acute full tissue thickness loss with associated crustacean and ciliates. 

• Occasional ciliates are present within gastrovascular canals. 

Recommendation: None. 

B 

Figure 29 A & B. Sloughing tissue in Acropora 

prolifera: A- field photo (Dana Williams); Bfixed specimen (Kathy Price).

A 
47

Figure 30 A & B. Photomicrographs of Acropora prolifera tissues fixed in seawater:Z-fix and 

stained with MHE: A- 10x, aggregates of ovoid basophilic bodies (not shown here, these are 

composed of basophilic rods) (↑); B- showing abrupt termination (↑) and crustaceans (►). 

A 

B 
48 

Slide 14

Signalment/History: Montastraea annularis (IRCP 18-2) collected from Tague Bay, 

US Virgin Islands collected on 10 July 1980 by Esther Peters. 

Field Diagnosis: Black band disease. 

Histopathology Description (Fig. 32): 

(Comment: Staining quality is poor; tissue not representative of black band edge.) 

Coenenchyme: No remarkable lesions are seen. 

Polyp: Near one edge of the section is a large sponge (Fig. 32A, ↑). The sponge 

tissue is separated from the coral tissue. There numerous endolithic organisms 

between the sponge and coral polyp. An adjacent polyp has vacuolization of the 

polyp epidermis (Fig. 32A, ►); it lacks nuclei and stains pale. There is loss of 

integrity (Fig. 32B, ↑) exemplified by cell lysis with release of zooxanthellae. 

Skeleton: Mats of non-staining wide structures with asymmetric walls and 

bulbous filaments are present, suggestive of endolithic fungi. 

Morphologic diagnosis: 

• Acute necrosis of polyps. 

• A focus of endolithic fungi. 

Addenda: The lesions observed were not related to black band mats. 

Recommendation: None. 

B 

Figure 31 A & B. Black band disease in Montastraea annularis: A- field photo (Esther Peters); Bfixed specimen, scale =1 cm (Esther Peters); taken from area adjacent (►) to diseased tissue (↑) as 

shown in Fig. 31A. 

A 
49

Figure 32 A & B. Photomicrographs of diseased Montastraea annularis tissues 

fixed in Helly’s and stained with MHE: A- 4x, showing a large sponge (↑) and 

polyp remnant (►) along with unidentifiable debris between the sponge and polyp; 

B- 10x, polyp fragmentation (↑); abundant endolithic fungi. 

B 

A 
50 

Slide 15 

Signalment/History: Acropora cervicornis (IRCP 178) collected from the Virgin 

Islands on 15 July 2004 by Lou Sileo, Thierry Work and Caroline Rogers. 

Field Diagnosis: Suspected snail predation. 

Histopathology Description (Fig. 34): 

Coenenchyme: Full tissue thickness loss culiminates in abrupt termination (Fig. 

34A, ↑). Epidermis is segmentally lost and gastrodermis is atrophied. Ova are 

abundant (Fig. 34B, ↑). Adjacent to intact tissue are scattered arthropods in the 

lumena of non-viable gastrovascular canals mixed with clumps of necrotic tissue 

characterized by aggregates of eosinophilic debris and karyorrhectic nuclei mixed 

with zooxanthellae. The deep gastrovascular canals are bereft of viable tissue, 

and this is more prominent at the edge of viable and non-viable tissue. There is 

diffuse depletion of zooxanthellae from gastrodermis. In deeper tissues, there are 

eosinophilic lamina (hyalinized mesoglea) sometimes associated with spiral and 

rod-shaped bacteria. 

Polyp: Within the mesoglea of a mesentery is a single irregularly round structure 

with central basophilic inclusions and a central nucleus surrounded by a vacuole 

(40-60 μm) (Fig. 34C, ↑). Also within mesenteries, within gastrodermal cells and 

near ova, are round brightly eosinophilic homogenous structures about the same 

size as zooxanthellae (Fig. 34C, ↑). Within deep gastrovascular canals, there is 

multifocal disassociation of gastrodermal cells of mesentery and attenuation of 

calicodermis (Fig. 34D, ↑). 

Skeleton: No remarkable lesions are seen. 

Morphologic Diagnosis: 

• Abrupt tissue loss of the coenenchyme and polyps. 

Figure 33 A & B. Suspected snail predation observed on Acropora cervicornis: A- field photo 

(Thierry Work); B- fixed specimen (Kathy Price). 

A B 
51

• Severe diffuse reduction of zooxanthellae in the gastrodermis and coenenchyme. 

• Focal sloughing of the gastrodermis and epidermis of the coenenchyme. 

• Multiple eosinophilic inclusions in the tissue of the gastrodermis surrounding the 

oocytes. 

Recommendation: None. 

Figure 34 A-D. Photomicrographs of Acropora cervicornis tissues fixed in seawater:Z-fix and stained by MHE: 

A- showing abrupt termination (↑); B- 2x, abundant ova (↑); C- 40x, brightly eosinophilic structures (↑) and 

zooxanthellae; D- 10x, disassociated gastrodermal cells (↑). 

A B 

C D 
52 

 WORKSHOP SUMMARY 

Workshop Achievements 

The goals and objectives set for the Workshop were met and exceeded. The following 

areas capture achievements from this workshop:

Nomenclature for Microscopic Anatomy of Corals 

The first formalized group effort to describe the histopathology of coral lesions was 

undertaken at this workshop. During the deliberations several of the participants 

expressed concern about the lack of adequate terminology for histopathologists to 

precisely describe the locations of lesions in hexacorals and octocorals. Several new 

terms were suggested that were thought to better identify tissues by function, recognizing 

that different etiologic agents can affect different functional tissues and have very 

different effects on the animal. As a result, the drafting of a white paper has been 

recommended that outlines the coral histopathology terminology dilemma, offers 

suggested terminology and definitions, and seeks critical review from the invertebrate 

zoology, histology, cell biology and pathology communities. 

Coral Lesion Description and Diagnostic Criteria 

Over 40 different coral ‘diseases and syndromes’ have been reported worldwide (Green 

and Bruckner 2000). Participants at this workshop conducted a histopathology review of 

15 lesions from 9 presumed disease conditions based on gross observations (aspergillosis, 

black band, dark spots, growth anomaly, yellow blotch, white band, white patch, white 

plague II and an unknown disease characterized by tissue sloughing) and one presumed 

physical damage (snail predation). These lesions were collected from 8 scleractinian 

coral species (Acropora cytherea, Acropora palmata, Acropora prolifera, Dichocoenia 

stokesii, Montastraea annularis, Montastraea faveolata, Siderastrea siderea) and one 

gorgonian species (Gorgonia ventalina). 

This review provided a consensus of microscopic findings associated with each of these 

lesions and consistent findings were noted for some of the field diagnosed diseases. 

These did not provide, however, definitive differential diagnostic characters for any of 

the diseases except gorgonian mycosis. The descriptions for all of the lesions though will 

provide benchmarks for future studies. 

Obviously these efforts were only the beginning of an in-depth, critical comparative 

review of coral lesions to confirm field diagnoses. There remain a number of disease 

lesions that were not reviewed. Many more descriptions of normal tissue and the 

histopathology associated with the lesions of recognized coral diseases will have to be 

added to these first attempts. It was also recognized that it is imperative for collection 

and processing techniques to be optimized with the goal of eliminating all autolysis, 

collection and processing artifacts. 

Advanced Training 

This workshop provided one of the first opportunities for board-certified medical and 

veterinary pathologists and invertebrate histopathologists to come together to exchange 
53

information, identify gaps in our knowledge of, and gain experience with, coral 

histopathology. This workshop served as a form of continuing education or crosstraining for all of the participants. As more individuals with experience in reading coral 

histology slides are trained to conduct coral histopathology, the field of coral pathology 

will grow. Their contributions along with the integration of information from marine 

biologists, microbiologists, virologists, toxicologists, and molecular biologists will 

provide more parameters to enhance the accuracy of differential diagnosis and 

elucidation of the pathogenesis and etiology of coral diseases. Bringing together the 

diversity of specialists needed to develop coral pathology is difficult, but their interest 

drives their involvement. We recognize that new means of facilitating these valuable 

interactions must be identified. One means to facilitate interactions and bring together 

specialists from remote locales is a new technology, introduced at this workshop, Virtual 

Slides. The Virtual Slide Technology allows connection among investigators via web 

conferencing to explore and develop coral microscopic anatomy and pathology. The 

participants recommended pursuing access to this technology to meet the needs of coral 

researchers, especially those in remote locations, interested in histology and 

histopathology for both education and consultation pursuits. 

Overall, the following were achieved at this workshop: 

a) A standardized approach for describing microscopic morphology. 

b) A standardized format for describing histology. 

c) The initiation of standardized nomenclature for microscopic anatomy of corals. 

d) Descriptions of 15 lesions using the above formats for corals from the Atlantic 

and Pacific. 

e) Consensus on a standardized format for histopathology reports, nomenclature for 

microscopic anatomy and pathology, and recommendations to improve 

histological features reached during this workshop will enable development of 

instructional materials and distance learning tools for coral histopathology. 

Coral pathologists must adopt strict standards for their field to become recognized by the 

medical and diagnostic communities. To take advantage of the depth and breadth of 

experience in those communities, standards must be adopted for (1) descriptors based on 

accepted medical terminology, (2) consistent and concise descriptions of lesions in the 

field, as well as (3) clinical morphological diagnoses in the laboratory and review of 

diagnostic criteria for new and emerging diseases among the coral pathology community. 
54 

RECOMMENDATIONS:

• Record the normal range of histological characteristics for the priority species of 

healthy corals in the Pacific and the Western Atlantic. This would include 

developing standardized methods to collect corals on a spatial and temporal basis 

and conduct histology using light and electron microscopy on selected specimens. 

• Develop a web-based virtual archive of coral histology and histopathology to 

facilitate contributions by new scientists to the field of coral health and to enhance 

the capabilities of existing scientists. 

• Disseminate the report via the Coral Reef Information System and other 

appropriate outlets. 

• Develop a white paper to justify the rationale for an internationally recognized 

systematic terminology for coral histopathology in consultation with experts in 

scientific nomenclature. 

• Conduct monthly reviews of coral lesions, using Virtual Slide technology and 

teleconferencing, to continue adding to the body of knowledge of coral 

histopathology. 

• Recommend the kinds of data necessary for epizootiological studies. These data 

need to be gathered during sample collections as they will not be available later. 

• Develop a standard protocol that identifies the type of samples and analyses 

needed based on known pathology and etiology of a disease from gross 

observations. 

• Develop GIS expertise within the consortium for mapping disease distribution, 

trends and environmental factors. 
55

ACKNOWLEDGEMENTS 

The generous contribution of time, effort and expertise from a number of individuals 

made the Coral Disease and Health Workshop: Coral Histopathology II and this 

publication possible. We offer a sincere thank you to all of you. 

We would like to recognize the Organizing Team, Drs. Lou Sileo, Shawn McLaughlin, 

Sylvia Galloway and Cheryl Woodley, who set the vision for the workshop, developed 

the agenda and identified expertise in key facets of pathology, histopathology and coral 

histopathology to establish a common nomenclature for the microscopic study of coral 

disease. Drs. Lou Sileo and Cheryl Woodley both deserve a special note of appreciation: 

Lou for his efforts and time prior to the meeting to devise a process to effectively 

generate a morphologic diagnosis and then his hard work to shepherd the group 

discussions to a productive end; and Cheryl for her leadership, working with those from 

disciplines other than her own, which has proven crucial in moving this coral 

histopathology effort forward. 

Particular thanks go to Ms. Julie Higgins (NOAA NOS CCEHBR) who jumped in to help 

with the final preparations for the workshop on her first day on the job and to Ms. 

Samantha Ryan for helping to transport workshop participants. 

We are especially grateful to NOAA’s International Registry of Coral Pathology and Dr. 

Shawn McLaughlin and Ms. Kathy Price for the many long hours they spent prior to the 

meeting preparing the histological slides and slide sets to allow individual and collective 

deliberations of representative coral lesions. Without these materials and this valuable 

resource (i.e., IRCP), this workshop just would not have happened. 

We would like to express sincere appreciation to the Department of Pathology and 

Laboratory Medicine at the Medical University of South Carolina who hosted the 

workshop. The assistance and accommodations provided by the Department were 

incredible. In particular, we appreciate the time Dr. Debra Hazen-Martin spent helping 

logistically and in various other critical matters to the workshop. We also appreciate the 

expertise in human pathology and wisdom that Dr. Russell Harley brought to the 

discussions. We are most grateful to Mr. James Nicholson who truly went beyond the 

call of duty in helping us in almost every facet of the meeting from setting up a webpage 

with frequent updates prior to the meeting to lending his expertise in all of the technology 

involved in this conference. Mr. Nicholson made arrangements to have high quality 

microscopes, cameras and going the extra-mile in digitizing slides to allow us to have 

access to the most current technology available in histology – virtual slides –for our 

deliberations. He also challenged confocal microscopy with coral tissue – live and fixed! 

And added such special touches as a group photo and a DVD of the images obtained 

during the meeting for each participant to take home. It is unlikely we would have 

accomplished as much as we did without his expert assistance, patience and dedication. 

Jim, we thank you. 
56 

We would like to thank Dr. Robert Ogilvie, MUSC Department of Cell Biology and 

Anatomy, for introducing us to a new digital technology that is revolutionizing histology 

and histopathology in the medical field. His presentation and the use of the virtual 

microscope opened a lot of eyes during the meeting, revealing just how powerful and 

useful this tool can be to share knowledge among pathologists and a significant 

enhancement to coral histopathology and its communications globally. 

We also thank Dr. Ogilvie and Aperio Technologies for bringing the ScanScope slide 

digitizer for demonstration at the workshop. Access to the Aperio System allowed us to 

exceed our expectations for the meeting. 

Dr. Sylvia Galloway deserves special recognition for the role she has played in producing 

this report. Her role began by serving as recorder during the four days of deliberation, 

where she so aptly synthesized the discussions for each participant to review and then 

facilitated bringing them to consensus on each pathology opinion that is offered in this 

report. Sylvia didn’t stop there, but has spearheaded the editing, layout and design of this 

publication. 

We must acknowledge Dr. Thierry Work for his contributions to the workshop and the 

generation of this publication. Thierry constantly kept us focused on the need for this 

workshop to have a useful product. During the meeting his initiative, drive and just plain 

energy, got us over some humps and propelled us into having a draft report before 

everyone left the meeting and well on the way to a finalized product within three weeks. 

Thierry we are exceedingly grateful for your leadership in this endeavor. 

We are especially grateful for the advice provided by four outside experts in anthozoan 

and coral anatomy and histology: Stephen Cairns, National Museum of Natural History, 

Smithsonian Institution; Daphne Fautin, University of Kansas; Walter Goldberg, Florida 

International University; and Jaroslaw Stolarski, Intytut Paleobiologii PAN. Their 

combined wisdom enabled us to provide strong definitions for several terms that were 

troubling to the workshop participants and thus will further good communication 

amongst coral biologists and histopathologists. 

We are particularly indebted to Dr. Esther Peters, a pioneer in the field of coral histology 

and histopathology for freely giving of her time and expertise both during the workshop 

and afterwards. Her detailed review/editing of this report insured that it is of high 

quality. In particular, we appreciate the refinement of the glossary that she and Dr. Esti 

Winter worked on together calling upon the expertise within the coral community to 

provide the most authoritative definitions. 

Financial support for this workshop was provided by NOAA through the Coral Reef 

Conservation Program. We also acknowledge the support of NOAA’s National Ocean 

Service Center for Coastal Environmental Health and Biomolecular Research. 
57

GLOSSARY of CORAL ANATOMY

and HISTOPATHOLOGY TERMS 

BACKGROUND

In the Introduction to the Glossary 

of Biochemistry and Molecular 

Biology, Glick (2006) states that “In 

the sciences, an essential aspect of 

recognizing, recalling and 

communicating something, be it a 

substance, relationship or method, 

is the naming of it. To create names 

for new concepts, methods or items, 

we invent new words, often using 

the roots of a Classical language 

(apoptosis, glycocalyx, isosbestic), 

and we recruit familiar words and 

invest them with new meanings 

(chaperone, kringle, library).” In 

either case, dictionaries and 

glossaries have become more 

important than ever in helping scientists understand what they are studying and to 

communicate new discoveries in rapidly evolving fields. Workshop participants realized 

early in the session that being able to communicate across coral biology, pathology, and 

histology might require reconsideration of pertinent terms and their definitions to make 

them applicable to coral histopathology and understandable to wider audiences. 

The definitions for the terms in this glossary have been derived from diverse sources, 

which are cited below and in the references at the end of this section. During and 

following the workshop, participants discussed the utility of terms currently used to 

describe the microscopic anatomy and pathology as it pertains to hexacorals and 

octocorals (= corals) and suggested including a glossary in the report to assist in 

explaining the histopathological findings from the coral sections reviewed by the 

participants. Most of the anthozoan anatomical terms were developed from dissections 

and histological studies used to distinguish taxa. Polyp features have been largely based 

on studies of sea anemones and octocorals, and primarily skeletal features have been used 

to distinguish taxa among scleractinians. Histological examinations of corals have 

expanded to include the study of diseases only since the late 1970s. The participants 

agreed that most descriptors commonly used in the evaluation of vertebrate disease 

processes could be adapted to the study of coral diseases; however, some new terms 

might be needed to facilitate interpreting the histological observations being made of 

coral specimens and making morphological diagnoses. 

Esther Peters points out specialized anatomical structures 

to workshop participants. 
58 

Some terms were confusing to veterinary and comparative histopathologists and some 

anatomical terms did not appear to adequately distinguish regions that consist of similar 

cell types but have different functions and might show different reactions when diseased. 

For example, “column wall” fits the cylindrical body of an anemone polyp, but should 

this be used for the colonial polyps embedded in mesoglea or skeleton? Is there a term 

that could be used to specifically identify the location of lesions in the part of the polyp in 

contact only with the skeleton or only with the seawater? Are other modifiers needed 

with “epidermis” and “calicoblastic epidermis”? Participants debated using the term 

“integument” to identify the unit of the three layers of cells and mesoglea forming the 

polyp, with modifiers of “paralithic” or “paramaric” to mean “beside the stone 

(skeleton)” or “beside the sea.” The term “calicoblastic layer” has been used to mean the 

unit composed of calicoblastic epidermis-mesoglea-gastrodermis, but “layer” means only 

a single thickness of cells or of a homogeneous substance. Participants proposed writing 

a white paper to justify the rationale for an internationally recognized terminology for 

coral histopathology in consultation with experts in the scientific nomenclature of coral 

anatomy and histology. 

During preparation of the workshop 

report, proposed and confusingly 

defined terms were presented to 

four outside experts in anthozoan 

and coral anatomy and histology: 

Stephen Cairns, National Museum 

of Natural History, Smithsonian 

Institution; Daphne Fautin, 

University of Kansas; Walter 

Goldberg, Florida International 

University; and Jaroslaw Stolarski, 

Intytut Paleobiologii PAN. The 

experts had diverse opinions as to 

the appropriateness and need for 

these terms, but all urged caution in 

developing new terms. Dr. 

Stolarski noted that separating 

human bones into those that are completely inside the body and those that extrude as 

limbs might be “useful for casualty ward but awkward for perfectly homologous 

structures.” 

But we are talking about the “casualty ward” for corals here and finding pathological 

changes in just the epidermis in contact with seawater rather than the epidermis that aids 

in skeletal deposition mean differences in organism function and prognosis for the 

animal, much as a broken ulna versus a broken pelvis do in humans. After more 

consideration, thought, and much research in publications, glossaries, and dictionaries, 

one new term is presented in this proposed glossary (“calicodermis,” marked with an “*” 

below). Other terms that have been in long use for anthozoans were found to be 

appropriate for the corals. 

Workshop participants discuss pros and cons of 

terminology; T. Work, C. Woodley, and L. Sileo.
59

The terms that generated the most discussion were “ectoderm,” “endoderm,” 

“epidermis,” and “gastrodermis.” Workshop participants were familiar with the use of 

the first two terms in developmental biology to refer to the outer and inner layers of cells 

that form during development of an embryo from the blastula into the gastrula. The 

cnidarian literature presented references to “ectoderm” and “epidermis” as the outer layer 

of cells of a polyp and “endoderm” or “entoderm” and “gastrodermis” as the inner layer 

of cells of a polyp. Libbie Hyman assigned the term “epidermis” to the outer adult 

cnidarian epithelium and proposed the term “gastrodermis” for the inner adult cnidarian 

epithelium, noting that “ectoderm” and “endoderm” were embryological terms ((Hyman 

1940), her first volume in The Invertebrates series). Fautin and Mariscal (1991) used 

“epidermis” and “gastrodermis” in their chapter on Anthozoa in Volume 2 of the 

Microscopic Anatomy of Invertebrates series. Because of this and usage of “epidermis” 

and “gastrodermis” in other recent anthozoan published works, including the Illustrated 

Trilingual Glossary of Morphological and Anatomical Terms Applied to Octocorallia

(Bayer et al. 1983), the workshop participants included these four terms in the glossary, 

noting their application to the embryological or adult epithelial layers. 

In her review of the draft glossary, Dr. Fautin stated that “ectoderm” and “endoderm” 

refer to the embryological development of the inner and outer layers of cells only in 

triploblastic animals. She noted that the editor of Volume 2, Jane Westfall, had insisted 

that Fautin and Mariscal use the terms “epidermis” and “gastrodermis” despite their 

protests that “ectoderm” and “endoderm” were originally assigned to identify the outer 

and inner epithelia of adult cnidarians and were later appropriated for embryonic cell 

layers in the context of ontogenetic recapitulation of the adult layers of Cnidaria. She 

further reported that Hyman, in her final volume VI (1967), wrote “In a project of such 

magnitude some errors of fact and judgment are inevitable. It was a mistake on my part 

to replace the terms ectoderm and entoderm on the grounds that they are embryological 

terms. They were in fact created by Allman for the two body layers of coelenterates 

[cnidarians]. I advise that gastrodermis be dropped and regret having introduced it.” In 

conclusion, she stated that Westfall now regrets having enforced its use (D. Fautin, pers. 

comm.). 

The workshop participants discussed these arguments. Although some sources use 

“ectoderm” or “ectodermis” to refer to the outer cell layer and “endoderm” or 

“endodermis” to refer to the inner cell layer in adult Cnidaria, these epithelia change in 

composition and function as the animal grows. The simple endoderm and ectoderm 

established during gastrulation are not the same as fully differentiated adult tissues in any 

eumetazoan, whether it is diploblastic or triploblastic. In the Cnidaria, the cells within 

each layer differentiate first into ciliated supporting cells, and then other cell types 

differentiate (e.g., mucocytes or nematocytes) or other functions are expressed (e.g., cells 

of the outer polyp layer develop microvilli for nutrient uptake or secrete an organic 

matrix for calcification; stem cells form amoebocytes or germ cells as needed for defense 

or reproduction; cells lining the gastrovascular cavity develop the ability to maintain 

zooxanthellae without harming them). Thus, the adult epithelia are not the same as the 

layers in the gastrula. 
60 

After much debate among participants and reviewers, “epidermis” and “gastrodermis” 

were included in the glossary as the terms for the adult epithelia that are derived from the 

embryonic ectoderm and endoderm, respectively. “Calicodermis” is the ectoderm that 

assists in building the calcified exoskeleton of scleractinians after the planula settles on 

the substratum. This term was proposed to shorten the currently used “calicoblastic 

epidermis” and to correct the misunderstanding that cells here are “calicoblasts” because 

they do not secrete the crystals of aragonite. Instead, the organic matrix, secreted by 

these cells, aids in the deposition of the crystals within the space between the cells and 

the skeleton. 

As noted by one of the participants, most terms and descriptors of microscopic anatomy 

and pathological processes in human and veterinary medicine have evolved over the past 

centuries through a process of proposal, use, modification, incorporation into the 

published literature, and general acceptance. The vocabulary and nomenclature for coral 

histopathology will evolve similarly in time. 

The glossary below presents our best compilation of terms found in the literature to date. 

Sources of the definitions are cited; however, most definitions have been clarified to 

better explain their pertinence to usage in coral studies. Not all anthozoan anatomical 

terms are included here as we have focused on those terms that should be most 

commonly needed for light microscopic histopathological examinations of these 

organisms, not those that are additionally needed for taxonomic or ultrastructural 

descriptions. The literature cited should be consulted as needed for other coral 

anatomical terms, particularly for specific taxa, as well as for terms to describe 

pathological changes, as necessary. Note also that new discoveries in coral anatomy and 

histology probably remain, as recently found by Goldberg (2002a; 2002b) for 

Mycetophyllia reesi, and might lead to adoption of new terms in this field. 

GLOSSARY

(Terms highlighted in blue are linked back to their definition in this glossary) 

Aboral – region of polyp directly opposed to, away from, or remote from the mouth; the 

terms Basal or Proximal can also be used to describe this region. (Dorland 2006) 

Acrosphere – globular tip of scleractinian tentacle, containing numerous nematocytes. 

(Fautin 2005) 

Actinopharynx (preferred term; synonyms – stomodaeum, pharynx) – invagination 

of the epidermis to form a short muscular tubular passageway between the mouth and 

gastric cavity in a polyp, mostly lined with flagellated supporting cells. (Fautin 2005; 

Peters 2001) 

Acute – exposure to a pathogen or a health effect that is brief, intense, short-term, or 

severe. The terms acute and subacute as they refer to pathology in coral are not currently 

precise enough to apply to cellular/microscopic changes and these terms as they are used 
61

in the current document will refer only to colony-level (gross) observations. (Stedman 

1995) 

Amoebocyte – a cell possessing pleomorphic form and high elasticity, the principal 

cellular defense element of Cnidaria and typically found in the mesoglea. Granular 

amoebocytes contain small, dense, acidophilic granules in the cytoplasm, may secrete 

collagen fibers or sclerites, phagocytize and digest particulate matter, or differentiate into 

other cell types. (Fautin and Mariscal 1991) 

Amphophilic – having an affinity both for acid and basic dyes. (Pharma 2006) 

Anthocodia (plural Anthocodiae) – the distal part of an octocorallian polyp, bearing the 

mouth and tentacles. (Bayer et al. 1983) 

Anthostele (= Calyx) – the rigid part of polyps seen in some species of octocorals, often 

stiffened by sclerites, and into which the anthocodia may be withdrawn. (Bayer et al. 

1983) 

Antipathin – a material composed of proteins and chitin that forms the axis in an 

antipatharian (black coral). (Goldberg 1976) 

Apical– opposite of basal, situated near the apex or tip of a structure, as in the apical 

portion of a cell. (Stedman 1995) 

Apoptosis (a form of programmed cell death) – a morphologic pattern of cell death 

formation of cytoplasmic blebs, and fragmentation of the cell into membrane-bound 

affecting single cells, marked by shrinkage of the cell, condensation of chromatin, 

apoptotic bodies that are phagocytosed by other cells. (Dorland 2006; Stedman 1995) 

Aragonite – mineral variation of calcium carbonate (CaCO3) with a crystal structure 

different from the other two forms of CaCO3, vaterite and calcite. It is formed mainly by 

marine organisms (e.g., coral) that use it to make their shells and skeletons. (Coris 2006) 

Atrophy – diminution of tissues, organs, or entire body, as from death and reabsorption 

of cells, diminished cellular proliferation, decreased cellular volume, malnutrition, or 

lessened function. (Stedman 1995) 

Attenuated – thinned or weakened, cause unknown. (Stedman 1995) 

Autolysis – lysis, enzymatic digestion, of cells by the enzymes present within them. 

(Stedman 1995) 

Axial Polyp – the longest polyp of a group of polyps, which produces secondary 

(daughter) polyps by lateral budding from its body wall. (Bayer et al. 1983) 
62 

Axial Sheath – that part of the colonial coenenchyme immediately surrounding the axis 

in the octocoral taxa Gorgonacea and Pennatulacea, containing the longitudinal canals 

and characterized by sclerites commonly different in form from those of the overlying 

coenenchyme. (Bayer et al. 1983) 

Axis – inner supporting structure of Gorgonacea and Pennatulacea. It is usually 

composed of collagen (see Gorgonin); however, the antipatharian (black coral) axis 

consists of different proteins and chitin (see Antipathin). The axis can be mineralized in 

some groups, usually by magnesium calcite (as in sclerites), but in some, the mineral in 

the axis is aragonite and amorphous hydroxyapatite also occurs in some axial skeletons. 

(Bayer et al. 1983; Bayer and Macintyre 2001; Goldberg 1976; Holl et al. 1992) 

 

Axis Cortex – layer around the central chord or core of the axis, deposited by an axis 

epithelium. (Bayer et al. 1983) 

Axis Epithelium – layer of cells derived from ectoderm consisting of two types of cells: 

corticocytes (cells that produce the axis) and desmocytes (cells that attach the octocoral 

tissues to the axis). (Bayer et al. 1983) 

Basal - situated near the base of a structure in relation to a specific reference point, 

opposite of apical. (Stedman 1995) 

Basal Plate – aragonite structure built by the polyp at the bottom or base of the skeletal 

cup (corallite) enclosing a scleractinian polyp. (Stachowitsch 1992) 

Basophilic – denoting components of cells having an affinity for basic dyes under 

specific pH conditions. Basophilic compounds (e.g., nucleic acids) stain blue with 

hematoxylin in the ‘hematoxylin and eosin’ (H&E) staining procedure. (Pharma 2006) 

Body Wall – the three layers of tissues (epidermis, mesoglea, gastrodermis) that form the 

surfaces of the polyp, enclosing the gastrovascular cavity and, in colonial corals, the 

gastrovascular canals. (Bayer et al. 1983; Goldberg 2002b) 

Surface Body Wall – in contact with seawater, covering the coenenchyme, 

tentacles, oral disk, peristome, and polyp neck zone and anthostele (octocoral) or 

column (hexacoral). 

Basal Body Wall – the calicodermis*, mesoglea, and gastrodermis that covers the 

exoskeleton of the scleractinian coral, surrounding the gastrovascular cavity and 

canals. 

Actinopharynx Body Wall – the specialized (heavily ciliated or flagellated) 

epidermis, mesoglea, and gastrodermis that forms the actinopharynx. 

Calice – the upper open or oral surface of the corallite. (Peters 1984) 
63

Calicoblast – primary cell type of the calicodermis* that secretes the organic matrix 

involved in calcification and formation of the skeleton in the scleractinians. (Puverel et 

al. 2005) 

Calicodermis* (= Calicoblastic Epithelium) – the thin but complex layer of 

ectodermally derived cells around a scleractinian polyp whose primary function is 

building the exoskeleton. In a colonial coral, as new polyps are formed, the calicodermis 

continues as the cell layer immediately adjacent to the skeleton of the interconnecting 

gastrovascular canals in imperforate corals and completely surrounds the gastrovascular 

canals embedded in the exoskeleton in perforate corals. Most of the cells are modified to 

secrete an organic matrix that may have a crucial role in the formation of aragonite

crystals to form the exoskeleton. These cells, currently referred to as calicoblasts, do not 

form aragonite intracellularly. Other cells in the calicodermis are modified to attach the 

tissue to the exoskeleton (see Desmocyte). This epithelium can also contain mucocytes, 

pigment cells, or amoebocytes, but usually lacks cnidocytes. (Goldberg 2002b; Goldberg 

2001a; Peters 1984, Coral Histopathology Workshop 2005) 

Calyx (plural Calyces) – see Anthostele

Central Chord or Core – the central part of the axis, made of gorgonin alone, or 

gorgonin permeated with calcareous matter, sometimes hollow and cross-chambered, not 

always present. (Bayer et al. 1983) 

Chromophore Cell – amoeboid cell containing cytoplasmic pigment granules in the 

scleractinian genus Porites. The granules appear yellow to tan when stained with 

hematoxylin and eosin using incandescent light microscopy and are bright green in 

unstained polyp sections when using a filter for green fluorescent protein with 

epifluorescence microscopy. (Duerden 1902; Smith 2004) 

Chronic – long-term exposure to a pathogen or a prolonged health effect. The term 

chronic as it refers to pathology in coral is not currently precise enough to apply to 

cellular/microscopic changes and this term as used in the current document will refer 

only to colony-level (gross) observations. (Stedman 1995, Coral Histopathology 

Workshop 2005) 

Cilium (plural Cilia) – one of the motile extensions of the surface of an epithelial cell 

containing nine longitudinal double microtubules made of structural proteins arranged in 

a ring around a central pair. (Stedman 1995) 

Cinclide – small opening or “soft spot” in the body wall through which mesenterial 

filaments can be extruded. (Fautin and Mariscal 1991) 

Cnida (plural Cnidae) – a collagenous capsule that develops in a cnidocyte and contains 

a tubule or thread that everts when triggered. There are three types of cnidae: 

nematocysts, spirocysts, or ptychocysts. Cnidae are non-self-replicating organelles 
64 

secreted by the Golgi apparatus, and are the most complex secretory products in the 

animal kingdom. (Hessinger and Lenhoff 1989; Mariscal 1984) 

Cnidocyst – cnida. (Mariscal 1984) 

Cnidocyte – epithelial cell that can produce a cnida in the Cnidarians, see also 

Nematocyst and Spirocyst. (Mariscal 1984) 

Cnidoglandular Band (or Lobe) – the distal thickened rim or free margin along a 

mesentery. It consists of the median band or tract of a mesenterial filament containing 

nematocytes, ciliated columnar or collar cells, mucocytes, and granular gland (zymogen) 

cells, may have two lateral lobes distal to the median lobe, consisting mainly of 

nutritive/absorptive cells. (Fautin and Mariscal 1991; Goldberg 2002b; Hyman 1940) 

Coccidian – a single-celled organism belonging to the protistan Phylum Apicomplexa, 

characterized by merogony and a life cycle comprising both sexual and asexual stages, 

parasitic in epithelial cells of invertebrates and vertebrates. (Upton and Peters 1986) 

Coenenchyme – the tissues between and continuous with the polyps in a colonial 

anthozoan, consisting of the surface body wall and gastrovascular canals found either on 

the surface of or penetrating the skeleton (in hexacorals) or consisting of the surface body 

wall, gastrovascular canals, and solenia penetrating through the thick mesoglea stiffened 

with sclerites (in octocorals). The edge zone of the coenenchyme is that portion 

extending outside the peripheral polyps at the edge of a colony or outside the theca in a 

solitary coral. (Bayer et al. 1983; Stachowitsch 1992) 

Coenosteum – skeleton deposited outside and between the corallite walls of the polyps

of a colonial scleractinian. (Peters 1984; Stachowitsch 1992) 

Collar Cell – specialized cell found in the epithelia of the mesenterial filament and 

actinopharynx. Requires transmission electron microscopy to distinguish its 

characteristic feature, a cilium with shallow rootlet surrounded by fibril-linked microvilli, 

with small fibrous or lysosome-like apical inclusions. (Goldberg 2002b) 

Column – the body wall of an anemone, the cylindrical surface of a polyp. In a 

scleractinian, that portion of the polyp that can extend outside the calice. (Fautin 2005; 

Peters 1984) 

Columella – column-shaped skeletal projection of the central basal plate or modified 

inner septal edges, may be solid or not. (Peters 1984; Stachowitsch 1992) 

Corallite – the skeleton deposited by an individual polyp within a colony. (Peters 1984, 

Acropora Biological Review Team) 

Corallum – the entire skeletal structure formed by either a solitary (single corallite) or 

colonial (group of corallites) coral. (Peters 1984) 
65

Corticocyte – cell that produces gorgonin and forms the axis in a gorgonian. (Tidball 

1982) 

Costa – the extension of the septa outside the calice onto the coenosteum. (Peters 1984) 

Degeneration – a nonspecific term applied to retrogressive but sometimes reversible 

pathological change in cells or tissues, resulting in impairment or destruction of 

functions; deterioration; preferably the specific changes observed should be fully 

described. (Dorland 2006; Stedman 1995) 

Desmocyte – anchoring cell of the calicodermis* (scleractinian) or axis epithelium

(gorgonian), characterized by unique apical and basal modifications for attachment to 

skeletal surfaces and mesoglea respectively. (Chapman 1974; Goldberg 2001b; 

Muscatine et al. 1997) 

Diagnosis – the determination of the nature of a disease. (Stedman 1995) 

Field Diagnosis – made from the study of the macroscopic changes of a coral 

disease observed in the field. 

Laboratory Diagnosis – made by a chemical, virological, parasitological, 

microbiological, or immunological study of secretions, discharges, or tissues. 

Morphologic Diagnosis – made from an anatomical or histological study of the 

lesions present. 

Etiologic Diagnosis – the determination of the cause of the disease. 

Differential Diagnosis – a systematic comparison and contrasting of similar 

disease signs and findings to determine which of two or more diseases is 

considered to be most likely present in the organism, although one or more other 

diseases are considered less likely to be present but possible. (See also 

Pathognomonic) A differential diagnosis is also made to distinguish between 

closely related species in taxonomy. 

Disassociation (or Dissociation) – a separation of relationships, as in the separation of 

epithelial cells because of damage to the intercellular junctions. (Stedman 1995) 

Disease – any deviation from, or interruption of, the normal structure or function of any 

body part, organ, or system that is manifested by a characteristic set of signs and whose 

etiology, pathology, and prognosis may be known or unknown (Dorland 2006); any 

impairment that interferes with or modifies the performance of normal function, 

including responses to environmental factors such as nutrition, toxicants, and climate; 

infectious agents; inherent or congenital defects, or combinations of these factors. 

(Wobeser 1981) 
66 

Distal – that part of a structure situated away from the center of or point of origin, the 

extremity or distant part of a limb or organ, e.g., distal tentacle. For a polyp, the distal 

part is the oral end of the entire polyp. (Fautin 2005; Stedman 1995) 

Ectoderm – the outer layer of pluripotential cells in the embryo, after establishment of 

the primary germ layers during the gastrula stage of development. (Hyman 1940; 

Martindale et al. 2004; Stedman 1995 discussed the diploblastic versus triploblastic 

nature of cnidarians) 

Endocoel – the region of the gastrovascular cavity between two mesenteries belonging to 

the same pair; in the endocoel of nondirective mesenteries, the longitudinal retractor 

muscles on the mesogleal pleats of the two mesenteries protrude into the cavity; in the 

endocoel of directive mesenteries, the longitudinal retractor muscles on the mesogleal 

pleats are on the side of the mesenteries so they do not protrude into the cavity. (Fautin 

2005) 

Endoderm (or Entoderm) – the inner layer of pluripotent cells in the embryo, after 

establishment of the primary germ layers during the gastrula stage of development. 

(Hyman 1940; Martindale et al. 2004; Stedman 1995 discussed the diploblastic versus 

triploblastic nature of cnidarians) 

Endolithic – growing within a rock or any other hard inorganic substratum, e.g., coral 

skeleton. (Coris 2006) 

Eosinophilic – cell or tissue elements staining readily with eosin dyes, appear pink to red 

when using a hematoxylin and eosin staining procedure; sometimes referred to as 

“acidophilic.” (Pharma 2006) 

Epidermis – external epithelium of coral polyps and coenenchyme derived from the 

ectoderm, may be composed of columnar supporting cells (with apical specializations 

such as microvilli, cilia, or flagella), ciliated sensory cells, mucocytes, epitheliomuscular 

cells, cnidocytes, pigment cells, neurons, amoebocytes. The epidermis can be reduced in 

octocorals (supporting cells, sensory cells, cnidocytes, scleroblasts, mucocytes, 

amoebocytes) and may secrete a covering on basal parts of octocoral colonies. (Fautin 

and Mariscal 1991; Hyman 1940) 

Epitheliomuscular Cell – cnidarian cell in which the cell body is columnar and the 

nucleus is situated in the basal portion of the cell. It is joined to other epithelial cells in 

the epidermis or gastrodermis and has elongated basal cytoplasmic extensions containing 

actin and myosin filaments, known as muscle fibrils or myonemes. The extensions are 

perpendicular to the cell body and attach to the surface of the mesoglea, facilitating polyp 

movement and contraction. The apical surface of the cell may have a flagellum. (Fautin 

and Mariscal 1991) 
67

Epithelium – layer of cells covering both ectodermally and endodermally derived tissues 

of the polyp body and canals, bound together by various junctions and cementing 

substances to provide strength and mediate the exchange of metabolic and messenger 

molecules, and bound to and supported by basement membrane or basal lamina. 

(Dorland 2006; Stedman 1995) 

Euchromatic (= Orthochromatic) – denoting any tissue or cell that stains the color of 

the dye used, i.e., the same color as the dye solution with which it is stained. (Pharma 

2006) 

Exocoel – the region of the gastrovascular cavity between two mesenteries belonging to 

different pairs. Except for the exocoels flanking the directive mesenteries, retractor 

muscles do not protrude into an exocoel. (Fautin 2005) 

Filament – see Mesenterial Filament

Flagellum (plural Flagella) – single, elongate motile structure consisting of nine pairs of 

microtubules around two single central proteinaceous microtubules extending from the 

apical surface of an epithelial cell or tail of spermatozoan. (Stedman 1995) 

Full Thickness (= Transmural) – a lesion, wound, or process that involves all layers of 

a tissue: epidermis or calicodermis*, mesoglea, and gastrodermis. (Coral Histopathology 

Workshop 2005) 

Fusiform – spindle-shaped, tapering at both ends, as in a fusiform cell. (Stedman 1995) 

Gastric Cavity – see Gastrovascular Cavity

Gastrodermal Canal – see Gastrovascular Canal

Gastrodermis – the inner epithelium of a coral polyp derived from the embryonic 

endoderm, lining the gastrovascular cavity and polyp-connecting canals. Some cells in 

this epithelium are phagocytic to digest food particles, absorb nutrients, and release waste 

products; zooxanthellae often reside within membrane-bound vacuoles in these cells. 

The gastrodermis may also contain ciliated or flagellated supporting cells, cnidocytes, 

amoebocytes, sensory cells, mucocytes, and pigment cells. (Fautin and Mariscal 1991; 

Goldberg 2002a; Hyman 1940; Peters 1984) 

Gastrovascular Canal – a system of tubes lined with gastrodermis that connect the 

gastrovascular cavities of colonial coral polyps. The canals extend along the surface of 

the coenosteum in all colonial scleractinians; in some species additional canals extend 

from the gastrovascular cavities to penetrate through the coenosteum between polyps, 

forming a porous or perforated skeleton. In the octocorals, the gastrovascular canals are 

embedded in the mesoglea and connect to thinner canals called solenia. (Bayer et al. 

1983; Peters 1984) 
68 

Gastrovascular Cavity – the interior space of a coral polyp, also referred to as the 

coelenteron in anthozoans, the saclike cavity within a polyp connected to the mouth by 

the actinopharynx. (Bayer et al. 1983; Fautin and Mariscal 1991) 

Germ Cell – oocyte or spermatocyte; cell originating in the gastrodermis of a mesentery

that migrates into the mesoglea and develops into either an oocyte or spermatocyte. 

(Fautin and Mariscal 1991) 

Giemsa – a stain that contains both basic and acidic dyes and will therefore differentiate 

acidic and basic granules in granulocytes. It is also often used to stain tissue sections

suspected to contain protozoan parasites. (Pharma 2006) 

GMS – Grocott-Gomori’s Methenamine Silver Stain, a modification of Gomori’s 

methenamine-silver staining procedure for fungi in which sections are pretreated with 

chromic acid before addition of the methenamine-silver solution and then counterstained 

with light green to demonstrate black-brown fungi against a pale green background. 

(Pharma 2006; Stedman 1995) 

Gonad – gametogenic region of a mesentery in a polyp. (Fautin and Mariscal 1991) 

Gorgonin – a fibrous, collagenous protein that provides skeletal support for sea fans and 

other members of the octocoral order Gorgonacea. (Coris 2006; Hyman 1940) 

Granular Gland Cell (= Zymogen Cell) – secretory epithelial cell containing 

acidophilic granules (e.g., lysosomes) that are released into the gastrovascular cavity for 

extracellular digestion of prey. (Fautin and Mariscal 1991; Hyman 1940) 

Holdfast – the portion of an octocoral colony attaching it to or in the substrate. (Bayer et 

al. 1983) 

Hyalin – a translucent, homogenous, structureless, eosinophilic, albuminoid substance 

occurring in tissue degeneration. (Pharma 2006; Stedman 1995) 

Hyalination – process of deposition of a cellular amorphous homogeneous substance 

which stains bright red with hematoxylin and eosin. (Stedman 1995) 

Hyaline – having the properties of hyalin. (Stedman 1995) 

Hydropic – excess of water or watery fluid. (Stedman 1995) 

Hyperplasia – an increase in the number of normal cells in normal arrangement in a 

tissue or organ, increasing its size. (Dorland 2006; Stedman 1995) 

Hyphae – the fine, branching tubes which make up the body (or mycelium) of a 

multicellular fungus. (Pharma 2006) 
69

Imperforate coral – corals which have solid skeletons with no connections between the 

polyps. (Coris 2006) 

Infection – invasion and multiplication of parasitic organisms within the body. (Stedman 

1995) 

Inflammation – a fundamental pathological process aimed at destroying, diluting, and 

walling off the injurious agent. The process generally consists of a dynamic complex of 

cytological and chemical reactions that occur in affected tissues in response to an injury 

or abnormal stimulation caused by a physical, chemical, or biologic agent, including the 

local reactions and resulting morphologic changes, the destruction or removal of injurious 

material, and the responses that lead to repair or healing. (Dorland 2006; Sparks 1985; 

Stedman 1995) 

Karyolysis – swelling of the nucleus of a cell and gradual loss of its chromatin, indicated 

by paling of the basophilic reaction in hematoxylin and eosin staining. (Dorland 2006; 

Stedman 1995) 

Karyorrhexis – rupture of the nucleus of a cell and the chromatin disintegrates into small 

pieces, which are extruded from the cell. (Dorland 2006) 

Lesion – a wound or injury, or any pathologic change in the tissues. (Stedman 1995) 

Lesion Distribution – distinguished on the basis of number of that particular 

type of lesion (focal: single, localized area; multifocal: relating to, arising from, or 

occurring in more than one place; diffuse: spread about, not restricted; systemic: 

spread throughout the entire organism). 

Lesion Severity – semiquantitative, subjective ranking of the degree of damage 

or extent of pathological change seen in tissues or an organism (ranging from 

minimal: smallest amount or lowest limit; mild; moderate; marked; to severe: 

intensely or extremely bad, very poor condition, or greatest in degree or extent). 

Loculus (plural Loculi) – calcified area or fiber-filled space within an axis (the axial 

skeleton of a gorgonian) or a space within the gastrovascular cavity between septa

(interseptal loculus). (Bayer et al. 1983; Fautin 2005) 

Lysis – dissolution or destruction of cells or structures. Lyse means to break up, 

disintegrate, or to effect lysis. (Stedman 1995) 

Lysosome – a cytoplasmic membrane-bound vesicle containing a variety of glycoprotein 

hydrolytic enzymes (lysozymes) active at an acid pH, for digesting exogenous material 

such as bacteria or worn-out organelles of the cell. (Stedman 1995) 

Margin – a boundary, edge, or border, as of a surface or structure. In anthozoans, also 

where the polyp column meets the oral disk. (Fautin 2005; Stedman 1995) 
70 

Melanin – high molecular weight polymer of indole quinone produced by animals, this 

pigment can be black, brown, yellow, red, or violet. It is produced by gorgonian cells 

(corticocytes) to encapsulate infectious agents. (Petes et al. 2003; Pharma 2006) 

Melanized – characterized by deposition of melanin. (Stedman 1995) 

Mesenterial Filament – a convoluted, elongated or ribbonlike extension of the free inner 

edge of the mesentery, composed of cells which aid in capture and digestion of food. 

These filaments, which appear as white loops with translucent mesentery, may also help 

to protect the coral from substrate competitors and invaders by protrusion through the 

mouth or through temporary openings in the tissue. The free edge is the cnidoglandular

band, which may or may not be flanked by lateral ciliated tracts or lobes depending on 

the species and location along the edge. In octocorals, the filaments of the two 

mesenteries opposite the siphonoglyph are very long and heavily flagellated, whereas the 

remaining six are shorter and glandular. (Bayer et al. 1983; Goldberg 2002b; Peters 1984) 

Digestive Filament – specialized ciliated, thin, grossly translucent, unequally 

bilobed, stalk-like contractile structure with spatulate distal end found in the 

scleractinian coral Mycetophyllia reesi. One lobe contains cnidae, mucocytes, 

collar cells, and granular cells and it protrudes through the polyp mouth during 

feeding (this species lacks tentacles). It is histologically distinct from mesenterial 

filaments and is housed in mesenterial ducts, radially arranged specially modified 

tubular mesenteries connecting to the actinopharynx. (Goldberg 2002b) 

Mesentery – internal longitudinal partition of tissue providing structural support and 

increasing surface area, which is important in nutrition and fertility of anthozoans. A 

mesentery develops by infolding of the mesoglea and its lining gastrodermis from the 

body wall of the polyp. Multiple mesenteries are arranged radially within the 

gastrovascular cavity of the polyp (between the septa in scleractinian corals) and are 

attached to the oral disk. (Fautin 2005) 

Directive Mesentery – one of a pair of mesenteries attached to the actinopharynx

in which the mesogleal pleats of the longitudinal retractor muscles face away 

from each other, toward the exocoel. 

Nondirective Mesentery – one of a pair of mesenteries attached to the 

actinopharynx in which the mesogleal pleats of the longitudinal retractor muscles 

face each other, toward the endocoel. 

Complete Mesentery – extends from the body wall to attach to the 

actinopharynx. 

Incomplete Mesentery – the free inner edge does not reach the actinopharynx.
71

Mesoglea – the connective tissue of coral and all cnidarians consisting of collagenous 

fibers embedded in a gelatinous material or ground substance of highly hydrated protein 

and neutral polysaccharide polymers and containing amoebocytes and other cells. The 

proportion of matrix to fiber and cells in this layer varies with the species and its 

condition. (Fautin and Mariscal 1991; Peters 1984) 

Mesogleal pleat – sheets of myonemes known as longitudinal retractor muscles are 

anchored into mesoglea and pleated accordion-fashion so that the mesoglea is 

sandwiched between two monolayers of epithelia within the middle portion of a 

mesentery. (Fautin and Mariscal 1991; Peters 1984) 

Mucocyte – modified columnar epithelial cell with basal nucleus containing basophilic 

granules or spumous inclusions, also referred to as a mucous secretory cell or 

mucosecretory cell. The cell synthesizes and secretes mucus through an apical pore to 

aid in feeding, protection, and sediment removal. (Peters 1984) 

Mucus – protective secretion of mucocytes consisting of a polysaccharide-protein-lipid 

complex; it traps particles non-selectively, removes sediment, lubricates the passage of 

food within the actinopharynx (ciliary-mucus feeding) and helps digest it, provides 

protection against desiccation, and presents a barrier against environmental stresses, 

including salinity and temperature changes and exposure to UV radiation. Mucus may 

also be involved in self-recognition and the immune response of cnidarians. Some of the 

properties of mucus can be distinguished in histology by using a staining procedure 

involving alcian blue, periodic acid, and Schiff’s reagent (AB/PAS). (Brown and Bythell 

2005; Carson 1997; Fautin and Mariscal 1991; Goldberg 2002a) 

Mycosis – any disease caused by a fungus. (Pharma 2006) 

Myoneme – contractile portion of epitheliomuscular cell or muscle fibril (myofibril) 

contained within the plasma membrane that anchors it to the mesoglea. It is attached by a 

long peduncle or process to the nuclear-containing portion of the cell. Myonemes may be 

diffuse or clustered into longitudinal and circular contracting sheets of muscle. (Fautin 

and Mariscal 1991) 

Necrosis – cell death characterized by irreversible damage, the earliest of which is 

mitochondrial. Changes visible with light microscopy are nuclear (pyknosis, karyolysis, 

or karyorrhexis) and generally accompanied by cytoplasmic hyper-eosinophilia, 

shrinkage, or fragmentation. After such changes, the outlines of individual cells are 

indistinct and affected cells may become merged, sometimes forming a focus of coarsely 

granular, amorphous, or hyaline material. (Stedman 1995) 

Necrotic – pertaining to or affected by necrosis. (Stedman 1995) 

Nematocyst – a type of cnida, secreted by the Golgi apparatus, produced exclusively by a 

cnidocyte or nematocyte of the Cnidaria. It consists of a double-walled capsule and an 

elongated hollow, sometimes externally spiny tubule that evaginates on mechanical or 
72 

chemical stimulation to entangle or deliver toxin to prey or repel attackers. About 30 

types of nematocysts have been defined, based on morphology of the capsule and tubule. 

(Fautin and Mariscal 1991; Goldberg 2002b; Hessinger and Lenhoff 1989; Peters 1984) 

Nematocyte – cell that produces a nematocyst. (Mariscal 1984) 

Nematode – member of the Nematoda, a class of unsegmented helminthes with 

fundamental bilateral symmetry and secondary triradiate symmetry of the oral and 

esophageal structures. Many species are parasites. (Pharma 2006) 

Neoplasia – the pathological process that results in the formation and growth of a 

neoplasm. (Stedman 1995) 

Neoplasm – an abnormal tissue that grows by cellular proliferation more rapidly than 

normal and continues to grow after the stimuli that initiated the new growth cease. A 

neoplasm is often characterized by partial or complete lack of structural organization and 

functional coordination with the normal tissue, usually forming a distinct mass. 

(Stedman 1995) 

Neuron – multifunctional (combined characteristics of sensory, motor, inter- and 

neurosecretory neurons), morphological and functional unit of the nerve net consisting of 

the nerve cell body and processes, axon and dendrite(s) (sometimes these processes are 

referred to as neurites), communicating through electrical conduction or secretion of 

neuropeptides. (Fautin and Mariscal 1991; Grimmelikhuijzen and Westfall 1995) 

Nodule – a small node, a circumscribed mass of tissue, or knob-like or knotty swelling of 

tissue. (Stedman 1995) 

Nonseptate – not divided internally by partitions. (Stedman 1995) 

Oocyte – female sex cell or gamete, immature ovum. (Stedman 1995) 

Oral – describing the region of a coral polyp near or toward the mouth; the terms Apical

and Distal can also be used to describe this region. (Fautin 2005) 

Oral Disk – the part of the polyp through the center of which the mouth opens, including 

peristomal tissue and tentacles. (Peters 1984) 

Ovum – the mature female germ cell (egg; female gamete). (Coris 2006) 

Parasite – an organism that lives on (ectoparasite) or in (endoparasite) another organism 

and derives its nourishment from that host organism. (Stedman 1995) 

Pathogen – any virus, microorganism, or other substance causing disease. (Stedman 

1995) 
73

Pathognomonic – typical characteristic signs, findings, or pattern of abnormalities 

specific for a given disease and not found in any other condition. Few disease signs and 

findings are characteristic for a single disease (see also Differential Diagnosis). 

(Stedman 1995) 

Perforate coral – coral that has a porous skeleton with gastrovascular canals that connect 

the gastrovascular cavities of the polyps along the surface and through the skeleton. 

(Coris 2006) 

Peristome – the portion of the oral disk surrounding the mouth and inside the ring of 

tentacles; may be elevated. (Peters 1984) 

Pigment cell – basally located epithelial cell that produces pigmented granules (e.g., 

green fluorescent protein-like pigments, animal coloration pigment). The genus Porites

contains specialized pigment granule-producing amoeboid cells called chromophore 

cells. Note that phagocytes can contain lipofucsin pigment granules obtained from 

necrotic cells. (Duerden 1902; Peters 1984) 

Phagocyte – a cell capable of ingesting bacteria, foreign particles, and other cells, present 

on the lobes of the mesenterial filaments and elsewhere in corals. (Hyman 1940; Peters 

1984; Stedman 1995) 

Pharynx – see Actinopharynx

Pinnule – one of the lateral processes along the tentacle of an octocoral. (Bayer et al. 

1983) 

Planula (plural Planulae) – the ciliated planktonic larval stage of the coral, developing 

from the zygote, occasionally noted in histological sections. The planula undergoes 

metamorphosis upon settlement on a suitable substrate. Some species of corals produce 

free-swimming planulae and other species brood planulae within the gastric cavity for 

variable periods of time. (Peters 1984) 

Pleomorphic – polymorphic, occurring in more than one morphologic form. (Stedman 

1995) 

Polyp – the basic structural unit of an anthozoan, consisting of a sac-like cylindrical 

body, a basal (aboral) disk that may be modified to produce a calcium carbonate or 

gorgonin exoskeleton or attach the polyp to the substrate, and an oral disk bearing mouth 

and tentacles. (Peters 1984) 

Proximal – that part of a structure nearest to the point of origin on an organism, as in a 

part of a limb or organ, e.g., proximal portion of tentacle. For a polyp the proximal part 

is its base that is attached to a surface or in mesoglea or skeleton. (Fautin 2005; Stedman 

1995) 
74 

Ptychocyst – a type of cnida used in tube construction by burying anemones 

(Ceriantharia). These anemones build a tube into which they can contract for protection 

almost entirely from the everted flattened, sticky tubules of the ptychocysts that trap sand 

grains to form the tube. (Hyman 1940) 

Pyknosis – a condensation or reduction in size of the cell or its nucleus. Nuclear 

pyknosis is contraction of the nucleus to a deep staining irregular or round mass, a stage 

of necrosis or sign of cell death. (Pharma 2006; Stedman 1995) 

Pyknotic – characterized by pyknosis. (Stedman 1995) 

Pyrenoid – a small proteinaceous body found within the cytoplasm of zooxanthellae (and 

other phytoflagellates) and closely associated with the chloroplasts. It contains the 

enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), which adds carbon 

dioxide to the sugar ribulose-1,5-bisphosphate as it synthesizes and deposits 

polysaccharides. The pyrenoid is visible in fixed, stained sections of zooxanthellae as a 

small round refringent body surrounded by a pale staining starch sheath. (Dorland 2006; 

Leggat et al. 1999) 

Pyriform – pear-shaped. (Pharma 2006) 

Regeneration – reproduction or reconstitution of a lost or injured part or an entire 

organism. (Stedman 1995) 

Sclerite – minute magnesium-calcite element in octocoral mesoglea or axis. (Bayer et al. 

1983; Goldberg 1976) 

Scleroblast – cell within the mesoglea of octocorals that produces a sclerite. The sclerite 

may be formed intracellularly in some octocorals or by a combination of intra- and 

extracellular calcification. (Bayer et al. 1983) 

Section – a thin slice of tissue, cells, macroorganisms, or any material for examination 

under the microscope. (Stedman 1995) 

Cross – sliced at right angles (or transverse) to the longitudinal axis of the 

organism. A cross-section of a polyp is one sliced at right angles to the 

longitudinal axis running in the oral to aboral direction. A cross-section of a coral 

colony branch is one sliced at right angles to the longitudinal axis extending from 

the axial polyp to the base of the branch. 

Sagittal – sliced along or parallel to the longitudinal axis of the polyp or branch 

(see Cross for explanation of axes). 

Oblique – a diagonal cross section that is neither parallel to the longitudinal axis 

nor at right angles to this axis (see Cross for explanation of axes). 
75

Septum (plural Septa) – one of the vertical calcareous plates or partitions radiating from 

the corallite wall toward the central axis within the calice that provide support to the 

mesenteries. (Peters 1984) 

Primary – full plates/partitions that separate two sets of mesenterial pairs. 

Secondary – partial plates/partitions that separate mesenteries within a 

mesenterial pair. 

Signalment – identification of the organism whose health is being examined, by 

describing distinguishing peculiar, appropriate, or characteristic physical marks or signs 

(e.g., species name, age or stage in development, size, coloration, gross lesions) and 

collection site and date collected. The basic signalment is aided by including collection 

site information, the specific samples collected from the specimen for investigation, and 

other observations on the history of the specimen’s condition, to the extent known. 

(CDHC Workshop: Coral Histopathology II, this document page 20) 

Siphonoglyph – the strongly ciliated groove extending down the side of the 

actinopharynx to direct water into the gastrovascular cavity. Scleractinian polyps lack 

siphonoglyphs; a polyp of an octocoral, cerianthid, and zoanthid has one siphonoglyph; 

an antipatharian polyp has two siphonoglyphs; although an actinarian and 

corallimorpharian polyp usually has two siphonoglyphs, it may have none, one, three, or 

more of them. (Bayer et al. 1983; Fautin 2005; Hyman 1940) 

Skeleton – the structurally supporting matrix of aragonite crystals formed by a 

scleractinian on the outside of the polyp, technically an exoskeleton, or the structural 

support for an octocoral. (Bayer et al. 1983; Stachowitsch 1992) 

Solenium (plural Solenia) – in octocorals, a small canal lined with gastrodermis, 

penetrating the coenenchyme, forming a network, and fusing with the larger 

gastrovascular canals to interconnect the gastrovascular cavities of the polyps. (Bayer et 

al. 1983) 

Spermary – gonad producing male gametes within the mesoglea of a mesentery. It may 

appear as an unattached cyst-like structure within the gastrovascular cavity of a sectioned 

octocoral polyp, but the mesentery producing it is attached to the underside of the oral 

disk. (Bayer et al. 1983; Fautin and Mariscal 1991) 

Spermatocyte, Spermatozoan – male gamete or sex cell that contains the genetic 

information to be transmitted by the male. (Stedman 1995) 

Spirocyst – single-walled capsule which contains a tightly coiled tubule bearing 

microtubules that form a web of fine, adhesive microfibrillae when discharged for prey 

capture or attachment, produced by a spirocyte. (Goldberg and Taylor 1996; Mariscal 

1984; Peters 1984) 
76 

Spirocyte – a cell lacking a sensory cilium that produces the spirocyst and occurs only in 

anthozoans. (Fautin and Mariscal 1991) 

Stem Cell – any precursor cell, a cell whose daughter cells may differentiate into other 

cell types. The term “interstitial cell” or “I-cell” has been used in the literature to refer to 

undifferentiated cnidarian (particularly Hydrozoa) cells lying between epithelial cells or 

migrating through the mesoglea that differentiate into the germ cells, nematocytes, and 

other cell types as needed. The term is rarely used in discussions of Anthozoa. More 

recent resources did not include this term, and “interstitial cell” has other specific 

meanings in vertebrate histology. “Stem cell” has universal meaning in all organisms. 

(Fautin and Mariscal 1991; Hyman 1940; Stedman 1995; Thomas and Edwards 1991) 

Stomodeum – mouth and actinopharynx as it begins developing in the coral embryo and 

planula, is also often applied to the actinopharynx of the adult. (Hyman 1940; Stedman 

1995) 

Supporting cell – columnar cell of the epidermis or gastrodermis with central nucleus, 

may have apical specializations of microvilli, cilia, or flagella. (Goldberg 2002a) 

Tentacle – hollow, contractile extension of the polyp’s oral disk distal to the mesenteries, 

typically cylindrical, commonly tapering to a point but in some species terminating in a 

spherical acrosphere, and rarely branched. In octocorals, each tentacle has two 

diametrically arrayed rows of short pinnules. The tentacle’s internal cavity is continuous 

with the gastrovascular space, continuous with that of the main body. In most species, it 

is studded with nematocysts and/or spirocysts, either scattered or arrayed in batteries. 

Tentacles are typically used in food capture, defense, and sediment removal; in some 

species, some tentacles are specialized to take up dissolved organic matter from seawater. 

(Acropora Biological Review Team 2005; Peters 1984; Stachowitsch 1992) 

Theca – wall of the skeletal cup (corallite) surrounding the scleractinian polyp. 

(Stachowitsch 1992) 

Tinctorial – relating to coloring or staining. (Pharma 2006) 

Tissue – a collection of similar cells and the intercellular substances surrounding them 

united in the performance of a particular function. Cnidaria possess all four of the basic 

tissues: (1) epithelium, (2) connective, (3) muscle, and (4) nerve. (Dorland 2006; Hyman 

1940; Stedman 1995) 

Transmural – see Full Thickness

Vacuole – a tiny fluid-filled cavity or a membrane-bound vesicle formed in the 

protoplasm of a cell. (Dorland 2006; Stedman 1995) 

Vacuolated – having vacuoles. (Stedman 1995) 
77

Vacuolization (or Vacuolation) – formation or multiplication of vacuoles. (Stedman 

1995) 

Zooxanthellae – dinoflagellates (unicellular photosynthetic organisms) that live within 

the gastrodermal cells of some scleractinians, octocorals, sea anemones and other animals 

(not cnidarians), which give corals a characteristic brown coloration. Zooxanthellae 

provide energy in the form of photosynthate, use animal wastes (nitrogenous ones and 

carbon dioxide) and, in calcifying organisms, enhance calcification. (Peters 1984) 

Zymogen – Proenzyme, precursor of an enzyme requiring a change in the molecule to 

make it active. (Stedman 1995) 

REFERENCES 

Bayer, F. M., M. Grasshoff, and J. Verseveldt. 1983. Illustrated Trilinual Glossary of 

Morphological and Anatomical Terms Applied to Octocorallia. Leiden: E.J. Brill, 

Dr. W. Backhuys. 

Bayer, F. M., and I. G. Macintyre. 2001. The mineral component of the axis and holdfast 

of some gorgonacean octocorals (Coelenterata: Anthozoa), with special reference 

to the family Gorgoniidae. Proceedings of the Biological Society of Washington 

114: 309-345. 

Boulon, R., M. Chiappone, R. Halley, W. Jaap, B. Keller, B. Kruczynski, M. Miller, and 

C. Rogers. 2005. 'Atlantic Acropora Status Review Document.' Report to 

National Marine Fisheries Service, Southeast Regional Office. March 3, 2005, p. 

152 p + App. 

Brown, B. E., and J. C. Bythell. 2005. Perspectives on mucus secretion in reef corals. 

Mar. Ecol. Prog. Ser. 296: 291-309. 

Carson, F. L. 1997. Histotechnology: A Self-Instructional Text. American Society of 

Clinical Pathologists. 

Chapman, D. M. 1974. Cnidarian Histology, p. 1-92. In L. Muscatine and H. Lenhoff 

[eds.], Coelenterate Biology, Reviews and New Perspectives. Academic Press. 

Coris. 2006. NOAA's Coral Reef Information System, Glossary. 

Dorland, W. A. N. 2006. Dorland's Illustrated Medical Dictionary. Saunders, W.B. . 

Duerden, J. 1902. West Indian madreporarian polyps. National Academy of Sciences 7: 

399-648. 

Fautin, D. G. 2005. Interactive Glossary of Actinarian (Sea Anemone) Anatomical 

Terms. 

Fautin, D. G., and R. N. Mariscal. 1991. Cnidaria: Anthozoa, p. 267-358. In F. W. 

Harrison and J. A. Westfall [eds.], Placozoa, Porifera, Cnidaria, and Ctenophora. 

Microscopic Anatomy of Invertebrates. Wiley-Liss. 

Glick, D. 2006. Glossary of Biochemistry and Molecular Biology. 

Goldberg, W. 2002a. Feeding behavior, epidermal structure and mucus cytochemistry of 

the scleractinian Mycetophyllia reesi, a coral without tentacles. Tissue & Cell 34: 

232-245. 
78 

---. 2002b. Gastrodermal structure and feeding responses in the scleractinian 

Mycetophyllia reesi, a coral with novel digestive filaments. Tissue & Cell 34: 

246-261. 

Goldberg, W. M. 1976. Comparative study of the chemistry and structure of gorgonian 

and antipatharian coral skeletons. Marine Biology 35: 253-257. 

---. 2001a. Acid polysaccharides in the skeletal matrix and calicoblastic epithelium of the 

stony coral Mycetophyllia reesi. Tissue & Cell 33: 376-387. 

---. 2001b. Desmocytes in the calicoblastic epithelium of the stony coral Mycetophyllia 

reesi and their attachment to the skeleton. Tissue & Cell 33: 388-394. 

Goldberg, W. M., and G. T. Taylor. 1996. Ultrastructure of the spirocyst tubule in black 

corals (Coelenterata: Antipatharia) and its taxonomic implications. Marine 

Biology 125: 655-662. 

Green, E. P., and A. W. Bruckner. 2000. The significance of coral disease epizootiology 

for coral reef conservation. Biological Conservation 96: 347-361. 

Grimmelikhuijzen, C., and J. Westfall. 1995. The nervous systems of cnidarians. EXS 

72: 7-24. 

Hessinger, D. A., and H. M. Lenhoff. 1989. The biology of nematocysts. Academic 

Press. 

Holl, S. M., J. Schaefer, W. M. Goldberg, K. J. Kramer, T. D. Morgan, and T. L. 

Hopkins. 1992. Comparison of black coral skeleton and insect cuticle by a 

combination of carbon-13 NMR and chemical analyses. Arch. Biochem. Biophys. 

292: 107-111. 

Hyman, L. H. 1940. The Invertebrates: Protozoa through Ctenophora. McGraw-Hill 

Book Company. 

---. 1967. The Invertebrates. Mollusca McGraw Hill. 

Leggat, W., M. R. Badger, and D. Yellowlees. 1999. Evidence for an Inorganic CarbonConcentrating Mechanism in the Symbiotic Dinoflagellate Symbiodinium sp. 

Plant Physiol. 121: 1247-1255. 

Mariscal, R. N. 1984. Cnidaria: Cnidae, p. 57-68. In J. Bereiter-Hahn, A. Matoltsy and K. 

S. Richards [eds.], Biology of the Integument. Springer-Verlag. 

Martindale, M. Q., K. Pang, and J. R. Finnerty. 2004. Investigating the origins of 

triploblasty: `mesodermal' gene expression in a diploblastic animal, the sea 

anemone Nematostella vectensis (phylum, Cnidaria; class, Anthozoa). 

Development 131: 2463-2474. 

Muscatine, L., E. Tambutte, and D. Allemand. 1997. Morphology of coral desmocytes, 

cells that anchor the calicoblastic epithelium to the skeleton. Coral Reefs 16: 205-

213. 

Peters, E. C. 1984. A survey of the normal and pathological histology of scleractinian 

corals with emphasis on the effects of sedimentation stress. Dissertation. 

---. 2001. Coral Tissue Slide Reading Workshop. 

Petes, L. E., C. D. Harvell, E. C. Peters, M. A. H. Webb, and K. M. Mullen. 2003. 

Pathogens compromise reproduction and induce melanization in Caribbean sea 

fans. Mar. Ecol. Prog. Ser. 264: 167-171. 

Pharma. 2006. Medi-Lexicon, Medical Terms Dictionary. 

Puverel, S., E. Tambutte, D. Zoccola, I. Domart-Coulon, A. Bouchot, S. Lotto, D. 

Allemand, and S. Tambutte. 2005. Antibodies against the organic matrix in 
79

scleractinians: a new tool to study coral biomineralization. Coral Reefs 24: 149-

156. 

Smith, C. B. 2004. Water clarity flux due to variable light intensity and its effects on 

fluorescent proteins of Porites porites: A hard coral from the tropical Western 

Atlantic. PhD dissertation. George Mason University. 

Sparks, A. K. 1985. Synopsis of Invertebrate Pathology Exclusive of Insects. Elsevier 

Science Publishers. 

Stachowitsch, M. 1992. The Invertebrates: An Illustrated Glossary. Wiley-Liss. 

Stedman, T. 1995. Stedman's Medical Dictionary, 26th Edition ed. Williams & Wilkins. 

Thomas, M. B., and N. C. Edwards. 1991. Cnidaria: Hydrozoa, p. 91-183. In F. W. 

Harrison and J. A. Westfall [eds.], Placozoa, Porifera, Cnidaria, and Ctenophora. 

Microscopic Anatomy of Invertebrates. Wiley-Liss. 

Tidball, J. G. 1982. An ultrastructural and cytochemical analysis of the cellular basis for 

tyrosine-derived crosslinks in Leptogorgia virgulata (Cnidaria: Gorgonacea). Cell 

Tissue Res. 22: 635-645. 

Upton, S. J., and E. C. Peters. 1986. A new and unusual species of Coccidium

(Apicomplexa: Agamococcidiorida) from Caribbean scleractinian corals. J. 

Invertebr. Pathol. 47: 184-193. 

Wobeser, G. A. 1981. Diseases of Wild Waterfowl. Plenum Press. 
80 

AGENDA

Coral Disease and Health Workshop: Coral Histopathology II 

Medical University of South Carolina (MUSC) 

Department of Pathology and Laboratory Medicine 

Walton Research Building 

Room RS-106 & RS-107 Module 5 

39 Sabin Street, Charleston, SC 

July 11-14, 2005 

Monday, July 11th

1:00-5:00 pm ScanScope virtual slide scanning demonstration at MUSC for early 

arrivals (Aperio Technologies)

Evening Reception - (Dr. Sylvia Galloway’s House – James Island)

Tuesday, July 12th

8:30 am Welcome – Cheryl Woodley, Ph.D. CDHC 

 NOAA NOS CCEHBR 

 Marine Biomedicine & Environmental Sciences 

 Debra Hazen-Martin, Ph.D. MUSC 

 Jim Nicholson, MUSC 

 Department of Pathology and Laboratory 

 Robert Ogilvie, Ph.D. MUSC 

Department of Cell Biology and Anatomy 

9:00 am Introductions 

 

Dr. Lou Sileo will outline the work plan and expected final products of 

the workshop: 

(1) An illustrated glossary of lesion descriptors and morphological 

diagnoses for coral lesions 

(2) Descriptions of the histopathology of specific “diseases” of coral 

10:00-Noon Demonstration of ScanScope virtual slide scanner 

12:30-5:00 pm** Coral Histopathology Review

 Practicing coral histopathologists will review the microscopy of 

coral abnormalities. A glossary of lesion descriptors and 

morphologic diagnoses will be developed during this review – 

Facilitator, Dr. Lou Sileo. 

• These reviews will be formatted from an organ perspective. 

• The group will discuss and reach consensus on a conceptual 

framework for the ‘blind’ review of glass slides of coral lesions 

Development of terminology for the description of coral lesions. 

• Pathologists will begin private examination of the glass slides from 

the first selected lesion without reference to the history information 

followed by group discussions at the multi-headed scope with 

projection screen. 

• A composite description of the lesion is formulated by the group 

for use in diagnostic criteria development. Once all individual 

observations have been synthesized into a composite description 
81

of the lesion, photos of the gross lesion will be presented along with 

the field diagnosis. 

Wednesday, July 13th 

8:30-5:00 pm** Continue ‘blind’ review, group discussions and description 

development of selected coral lesions (e.g., growth anomalies, 

disease, physical damage) 

Thursday, July 14th

8:30-5:00 pm ** Continue ‘blind’ review, group discussions and description 

development of selected coral lesions (e.g., growth anomalies, 

disease, physical damage) 

Compare and synthesize the descriptions of lesions from the same 

“disease” 

Polish the ‘glossary of lesion descriptors and morphologic 

diagnoses’, and integrate these into the Diagnostic Key developed 

at Madison Workshop 

Plan workshop report and website information 

**May extend past 5pm on certain days as warranted. 
82 

WORKSHOP PARTICIPANTS (top left to bottom right): Valerie Bochsler, Sylvia 

Galloway, Russell Harley, Pam Parnell, Taylor Reynolds, Esther Peters, Louis Sileo, 

Cheryl Woodley, Carol Meteyer, Shawn McLaughlin, Frank Morado, Esti KramarskyWinter, David Rotstein, Thierry Work. 
WORKSHOP PARTICIPANTS: 

Valerie Shearn-Bochsler, DVM 

USGS National Wildlife Health Center 

6006 Schroeder Rd 

Madison, WI 53711 

Phone: (608) 270-2457 

Fax: (608) 270-2415 

Email: vbochsler@usgs.gov

Sylvia B. Galloway, PhD 

NOAA/CCEHBR & 

Marine Biomedicine and 

Environmental Sciences Program 

Medical University of South Carolina 

221 Ft. Johnson Road 

Charleston, SC 29412 

Phone: (843) 953-0772 

Fax: (843) 953-0774 

Email: sylvia.galloway@noaa.gov

Russell Harley, MD 

Pathology & Laboratory Medicine 

MUSC Medical Center 

165 Ashley Avenue 

PO Box 250908 

Charleston, SC 29425 

Phone: (843) 792-4444 

Email: harleyr@musc.edu

Esti Kramarsky-Winter, PhD 

Dept. of Zoology 

George S Wise Faculty of Life Sciences 

Tel Aviv University 

Tel Aviv, Israel 69978 

Phone: 972-3-640-9809 

Fax: 972-3-640-7682 

Email: wintere@post.tau.ac.il

Shawn M. McLaughlin, PhD 

NOAA National Ocean Service 

904 S. Morris St. 

Oxford, MD 21654 

Phone: (410) 226-5193 

FAX: (410) 226-5925 

Email: shawn.mclaughlin@noaa.gov

Carol Uphoff Meteyer, DVM, 

Diplomate ACVP 

Wildlife Pathologist 

USGS – National Wildlife Health Center 

6006 Schroeder Rd 

Madison, WI 53711 

Phone: (608) 270-2462 

Email: carol_meteyer@usgs.gov

Frank Morado, PhD

NOAA, National Marine Fisheries Service 

Alaska Fisheries Science Center 

7600 Sand Point Way, N.E. 

Seattle, WA 98115-0070 

Phone: (206) 526-6572 

Email: Frank.Morado@noaa.gov

Pamela G. Parnell, DVM, PhD, 

Diplomate ACVP 

Director, Clemson Veterinary Diagnostic Center 

PO Box 102406 

Columbia, SC 29224-2406 

Phone: (803) 788-2260 ext 245 

Fax: (803) 699-8910 

Email: pprnll@CLEMSON.EDU

Esther Peters, PhD 

4016 Whispering Lane 

Annandale, VA 22003 

Phone: (703) 642-1289 

Email: esther.peters@verizon.net

Taylor Reynolds, DVM 

Department of Pathobiology 

Johns Hopkins University 

School of Medicine 

720 Rutland Avenue, Ross 558 

Baltimore, MD 21205 

Phone: (443) 287-3163 

Email: treynol6@jhmi.edu

David S Rotstein, DVM, MPVM, 

Diplomate ACVP 

Assistant Professor, Department of Pathobiology 

College of Veterinary Medicine 

University of Tennessee 

2407 River Drive, Room A201 

Knoxville, TN 37996-4542 

Phone: (865) 974-8205 

Email: drotstein@mail.ag.utk.edu

Lou Sileo, PhD 

USGS, National Wildlife Health Center 

6006 Schroeder Rd. 

Madison, WI 53711 

Voice: (608) 270-2461 

Fax: (608) 271-2415 

Email: lou_sileo@usgs.gov 
84 

Cheryl Woodley, Ph.D. 

DOC/NOAA/NOS/NCCOS 

Center for Coastal Environmental 

Health and Biomolecular Research 

Hollings Marine Laboratory 

331 Fort Johnson Rd 

Charleston, SC 29412 

Phone: (843) 762-8862 

Fax: (843) 762.8737 

Email: cheryl.woodley@noaa.gov

Thierry M. Work, DVM 

USGS-National Wildlife Health Center 

Honolulu Field Station 

PO Box 50167 

Honolulu, HI 96850 

Phone: (808) 792-9520 

Fax: (808) 792-9596 

Cell: (808) 554-6490 

Email: Thierry_work@usgs.gov

Support provided by: 

Debra Hazen-Martin, PhD 

Pathology & Laboratory Medicine 

MUSC Medical Center 

165 Ashley Avenue 

PO Box 250908 

Charleston, SC 29425 

Phone: (843) 792-2906 

Email: Hazenmad@musc.edu 

Julie Higgins, MS 

DOC/NOAA/NOS/NCCOS 

Center for Coastal Environmental 

Health and Biomolecular Research 

Hollings Marine Laboratory 

331 Fort Johnson Rd 

Charleston, SC 29412 

Phone: (843) 762-8959 

Fax: (843) 762-8737 

Email: julie.higgins@noaa.gov

James Nicholson 

Pathology & Laboratory Medicine 

MUSC Medical Center 

165 Ashley Avenue 

PO Box 250908 

Charleston, SC 29425 

Phone: (843) 792-4158 

Email: micholsj@musc.edu 

Robert W. Ogilvie, PhD 

Department of Cell Biology and Anatomy 

173 Ashley Avenue 

MUSC Medical Center 

P.O. Box 250508 

Charleston, SC 29425 

Phone: (843) 792-2667 

Email: ogilvieb@musc.edu

Samantha Ryan 

DOC/NOAA/NOS/NCCOS 

Center for Coastal Environmental 

Health and Biomolecular Research 

Hollings Marine Laboratory 

331 Fort Johnson Rd 

Charleston, SC 29412 
United States Department of Commerce 

Carlos M. Gutierrez 

Secretary 

National Oceanic and Atmospheric Administration 

Vice Admiral Conrad C. Lautenbacher, Jr. USN (Ret.) 

Under Secretary of Commerce for Oceans and Atmosphere 

National Ocean Service 

John (Jack) H. Dunnigan 

 Assistant Administrator for Ocean Service and Coastal Zone Management 
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