bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology of congenital microphthalmia in chicks (Gallus gallus)
Authors: Ehrlich David , Stuchbery John , Zappia Joe
Published: February 2005

This study examines the morphology of sporadic congenital microphthalmia in 1‐day‐old chicks, with particular emphasis on the neural retina. On the basis of the size of the eyeball it is possible to classify microphthalmia into two groups, severe and mild. In severe microphthalmia (less than 5 mm in equatorial diameter), the eyeball is severely malformed, but in most cases it shows evidence of an organized neural retina. Although ganglion cells and an optic nerve head are present in a small proportion of these retinae, we could not trace an optic nerve projection to the brain. These results indicate that some ganglion cells are able to be sustained after the period of naturally occurring cell death, suggesting either that those ganglion cells have established some contact with the central nervous system or that the presence of their axons in a rudimentary optic nerve is adequate for survival. In mild microphthalmia (greater than 5 mm in equatorial diameter), the most consistent abnormality is a defect in the pecten, which together with other abnormalities such as orbital cysts and colobomas indicates that the major abnormality occurs in the region of the choroid fissure. Associated with these defects are abnormalities within the ganglion cell layer. In some cases the number of ganglion cells was reduced, and in others the numbers of both ganglion and displaced amacrine cells were reduced. Unexpectedly, there were localized regions completely devoid of cells in the ganglion cell layer. The timing of the congenital defect may provide some clue as to the presence of a critical period in which displaced amacrine cells are formed or are sensitive to events related to ganglion cell loss.
A novel intercellular junction between cone cells in the compound eye of Ephestia kuehniella
Authors: Hollander Brian A. , Imberski Richard B.
Published: February 2005

A previously unidentified intercellular junction between cone cells in the compound eye of the moth Ephestia is described. The junctions are characterized by deposition of granular material, in register, along portions of the membranes of adjacent cone cells during compound eye development and by a constant intercellular space of 8–10 nm. Accumulation of the cone cell material along localized regions of the cell membrane suggests an interaction between a specialized area of the membrane and a specific cytoplasmic constituent, and the exact matching of the regions of deposition between adjacent cells implies intercellular interaction. The junctional nature of these membrane regions is often obscured in the adult crystalline cone but is inferred from observations on developing cone cells.
Ultrastructural changes in the connective tissue of the gastric region during the metamorphosis of Xenopus laevis
Authors: Ishizuya‐Oka Atsuko , Shimozawa Atsumi
Published: February 2005

Development of the gastric connective tissue of Xenopus laevis during metamorphosis was investigated by electron microscopy. Throughout the larval period to stage 60, the layer of connective tissue underlying the gastric epithelium consists of immature fibroblasts surrounded by a sparse extracellular matrix. At the beginning of the transition from the larval to the adult epithelial form, at about stage 60, extensive changes occur in the connective tissue. The number of cells suddenly increses and different cell types appear. Numerous contacts between epithelial and connective tissue cells are established through random gaps in the thickened basal lamina. During stages 62–63, just after the beginning of the morphogenesis of adult‐type glands, the basal lamina lining the glandular epithelium becomes thinner, and the number of contacts decreases rapidly except near the tips of the glands. After the glandular cells begin to produce zymogen granules at stage 64, contacts become rare. From stage 63, when the muscularis mucosae develops, until the completion of metamorphosis, the connective tissue consists mainly of typical fibroblasts. Outside the muscularis mucosae, the fibroblasts of the lamina propria are aligned in parallel with the curvature of the glands. These observations indicate that developmental changes in the connective tissue are closely related spatiotemporally to those of the epithelial transition from larval to adult form during metamorphic climax. Although some changes are similar to those in the intestine (Ishizuya‐Oka and Shimozawa, '87b), others are specific to the gastric region, which suggests that connective tissue may have a role in organ‐specific differentiation of the gastric epithelium.
Development of the turtle carapace: Implications for the evolution of a novel bauplan
Authors: Burke Ann Campbell
Published: February 2005

The chelonian carapace is composed of the endochondral ribs and vertebrae associated with a specialized dermis. The ribs are found in an aberrant position compared to those of all other tetrapods; they are superficial and dorsal to the limb girdles. This morphological arrangement, which constitutes the unique chelonian Bauplan, is examined from a developmental perspective. Embryos of Chelydra serpentina were studied during stages of carapace development. Tissue morphology, autoradiography, and indirect immunofluorescent localization of adhesion molecules indicate that the outgrowth of the embryonic carapace occurs as the result of an epithelial–mesenchymal interaction in the body wall. A carapacial ridge composed of mesenchyme of the dermis and overlying ectoderm is formed dorsal to the ectodermal boundary between somitic and lateral plate mesoderm. It is the anlage of the carapace margin, in which the ribs will eventually terminate. The ectoderm of the carapacial ridge is thickened into a pseudostratified columnar epithelium, which overlies a condensation in the mesenchyme of the dermis. Patterns of cell proliferation and the distribution of N‐CAM and fibronectin in the carapacial ridge are consistent with patterns seen in other structures initiated by epithelial–mesenchymal interactions such as feathers and limb buds.

Based on an analogy to this developmental mechanism in the development of the limb skeleton, a further analogy with the evolution of the limbs from lateral fin folds is used to form a hypothesis on the evolution of the carapace from elements of the primitive reptilian integument.
Sperm storage within the oviduct of turtles
Authors: Gist Daniel H. , Jones Jeffery M.
Published: February 2005

Tubules containing sperm were identified by light microscopy in the oviducts from 11 species of turtles representing six different families. Sperm storage tubules were found in a small region of the posterior portion of the egg albumin‐secreting section of the oviduct located between the infundibulum and the uterus. This location of storage tubules, midway between the ovary and vagina, is unique among vertebrates. Ducts, restricted to the posterior albumin region, connect the tubules to the oviduct lumen, allow entrance of sperm to the tubules. Sperm were identified in tubules of female turtles isolated from males for as long as 423 days.
Anatomy of the extrinsic gut musculature of Gammarus minus (Crustacea: Amphipoda)
Authors: Carlton Christopher E. , Schmitz Eugene H.
Published: February 2005

Inserting on the buccal and esophageal foregut of Gammarus minus are numerous pairs of serially arranged dorsal dilator muscles, a single pair of lateral muscles, and two pairs of posterior muscles. Muscles of the cardiac stomach include three dorsal sets, a single pair associated with the pterocardiac ossicles, and two pairs inserting on the ventral aspect. A single pair of muscles inserts on the lateral aspect of the pyloric stomach. The extrinsic muscles of the foregut originate from exoskeletal apodemes of the cephalothoracic cuticle, sockets of the mandible, and a maxillary bridge that lies just ventral to the cardiac stomach. The extrinsic musculature of the hindgut is restricted to the rectal region and consists of paired dorsal and ventral series in an X‐configuration. A single unpaired muscle inserts on the ventral midline. Extrinsic muscles of the hindgut originate from the integument of the last pleonic segment. The general arrangement of extrinsic gut muscles in G. minus is similar but not identical to that of other amphipods studied. However, the pattern is quite different from that of other malacostracans.
Analysis of the endocardium and cardiac jelly in truncal development in the cardiac lethal mutant axolotl Ambystoma mexicanum
Authors: Lemanski Larry F. , Fitzharris Timothy P.
Published: February 2005

Recessive mutant gene c in axolotls results in a failure of the heart to function because of abnormal embryonic induction processes. The myocardium in this mutant lacks organized sarcomeric myofibrils. The present study was undertaken to determine if developmental abnormalities were evident in other areas of the heart besides the myocardium. A detailed comparative survey of the structure of developing normal and mutant hearts, including the endocardium, its cellular derivatives, and the extracellular matrix, known as cardiac jelly, showed that in the mutant there are fewer than the normal number of endocardial cells lining the heart lumen, the number of mesenchyme cells is reduced, and the cardiac jelly area is greatly enlarged in the posterior part of the truncus adjacent to the ventricle.
Electron microscopic investigation relating the occlusal morphology to the underlying enamel structure of molar teeth of the wombat (Vombatus ursinus)
Authors: Ferreira J. M. , Phakey P. P. , Palamara J. , Rachinger W. A. , Orams H. J.
Published: February 2005

This investigation relates the occlusal morphology of the continuously growing molars of common wombats (Vombatus ursinus) to the underlying enamel ultrastructure that was investigated using the techniques of light microscopy, scanning electron microscopy, and transmission electron microscopy. The main feature of the occlusal enamel was a prominent ridge, which followed the contour of the dentine‐enamel junction (DEJ). It was found that the occlusal morphology depended upon the orientation of the dentinal and enamel tissues, variations in prism orientation, Hunter‐Schreger bands (HSB), and presence or absence of cleavage. Cleavage of enamel promoted by sheets of parallel prisms occurred along the face between the DEJ and the ridge, whereas on the face between the ridge and the cementum‐enamel junction (CEJ) cleavage was inhibited by HSB. The slope of the latter face was mainly due to a decrease in wear resistance going from the ridge, where prisms were intercepted transversely, toward the CEJ, where they were intercepted obliquely. Occasionally small surface undulations were observed on the face between the ridge and the CEJ. These undulations were found to correspond to gradually decussating enamel regions. The pronounced cleavage of enamel parallel to the face between the DEJ and the ridge played an important role in conferring on the continuously growing molars a distinct property to develop and maintain a self‐sharpening ridge throughout the life of the tooth.
Morphological comparison of major arteries in the ridgeback prawn, Sicyonia ingentis
Authors: Martin Gary G. , Hose Jo Ellen , Corzine Cathleen J.
Published: February 2005

The structure of the major vessels conducting hemolymph away from the heart of the ridgeback prawn, Sicyonia ingentis, was examined using light and electron microscopy. Three varieties of vessel wall morphology were observed. In most vessels the wall is composed of the following four layers, proceeding from lumen to exterior: (1) thick basal lamina, which selectively stains with Verhoffapos;s Van Giesonapos;s stain for elastin, (2) a continuous layer of cells rich in microtubules, (3) a loose connective tissue layer with highly branched cells widely separated by a fibrillar matrix, which also stains for elastin, and (4) a thin basal lamina covering the outer surface of the vessel. The dorsal abdominal artery shows the second type of vessel wall construction and differs from the previous vessels in the following ways: (1) the inner basal lamina is thinner, (2) a layer of striated muscle replaces the unspecialized endothelial layer, and (3) the connective tissue layer includes two well‐organized bands of elastin‐like material. The hematopoietic vessels that branch off the ophthalmic arteries display the third type of vessel wall morphology. The lumen of the vessel is lined by a very thin basal lamina, which completely encircles the endothelial cells. The rest of the wall is composed of hemocytes, presumably in various stages of maturation, embedded in a matrix of fibroblast‐like cells and collagen fibrils. The morphology of the vessel wall is the same as that previously described for the tubules of the hematopoietic nodules. The functional significance of these different vessel walls is discussed.
Spermiogenesis in the Nile tilapia Oreochromis niloticus with notes on a unique pattern of nuclear chromatin condensation
Authors: Lou Ya‐Huan , Takahashi Hiroya
Published: February 2005

Spermiogenesis in the Nile tilapia, Oreochromis niloticus, was observed ultrastructurally. The process of spermatid differentiation can be divided into six distinct stages based mainly on changes in the nucleus of spermatids. During the latter half of the process, nuclear chromatin condenses progressively to form many dense globules, which ultimately adhere tightly to pack the head of mature spermatozoa. During chromatin condensation the nucleus diminishes in size, and part of the nuclear envelope and nucleoplasm forms a vesicular structure that is finally discarded from the cells together with an associated thin layer of cytoplasm. The spermatozoon comprises a roundish head, a relatively small midpiece, and a relatively short flagellum consisting of the usual 9+2 axoneme. No acrosomal structure is developed during spermiogenesis.
Major ocular glands (Harderian gland and lacrimal gland) of the musk shrew (Suncus murinus) with a review on the comparative anatomy and histology of the mammalian lacrimal glands
Authors: Sakai Tatsuo
Published: February 2005

The Harderian gland of the musk shrew Suncus murinus is elongated anteroposteriorly from in front of the eye to behind the ear. The gland is divided into two portions: an anterior portion (A portion) and a posterior portion (P portion). The single secretory duct of the gland emerges from the anterior end of the P portion, receives several secretory ducts of the A portion during the course along it, runs around the ventral aspect of the eyeball, and finally opens into the anterior corner of conjunctival sacs. The two portions of the gland show a fundamentally similar histological structure, having a poorly developed intraglandular duct system and wide tubular alveoli. The quantity of lipid vacuoles and stromal connective tissue in the A portion is greater than in the P portion. The lipid vacuoles in both portions are surrounded by unit membranes, but their contents appear different.

The lacrimal gland of the musk shrew is located along the ventral side of the P portion of the Harderian gland. The lacrimal duct emerges from its anterior end, runs around the ventral and anterior aspects of the ear, crosses the A portion of the Harderian gapos; and, and finally opens at the posterior corner of conjunctival sacs. The lobules of the lacrimal gland comprise a branched duct system and terminal acini with two types of secretory cells: (1) acidic cells positive both for the periodic acid‐Schiff reaction (PAS) and for Alcian blue (AB) and (2) neutral cells positive for PAS and negative for AB. Both cell types tend to make separate acini, but when present in the same acinus, the acidic cells occupy relatively peripheral positions in the acinus. Both cell types lack intercellular canaliculi.

On the basis of the present study as well as previous descriptions in the literature, the author suggests that the mammalian lacrimal glands can be divided into two sets: (1) a Glandula lacrimalis superior with multiple secretory ducts associated with the upper eyelid and (2) a Glandula lacrimalis inferior with a single secretory duct opening into the lateral corner of the conjunctival sacs. These glands have a fundamentally similar histological structure; but in the rabbit, which possesses both sets of lacrimal glands, they are different. On the other hand, the secretory cells of lacrimal glands generally have no intercellular secretory canaliculi, which are characteristically present between the serous secretory cells of the salivary glands.
Structure of the ovotestis and evidence for heterosynthetic incorporation of yolk precursors in the oocytes of the nudibranch mollusc, Spurilla neapolitana
Authors: Eckelbarger Kevin J. , Blades‐Eckelbarger Pamela I.
Published: February 2005

The ovotestis of Spurilla neapolitana consists of a series of spherical lobes, each of which is composed of radially arranged, sac‐like acini or follicles. The male and female portions of each acinus are separated by ovarian follicle cells and testicular accessory cells. A thick basal lamina serves as a barrier between adjacent acini. The surface of each ovotestis lobe is covered by several layers of myoepithelial cells resting on a connective tissue layer. Developing oocytes are intimately associated with follicle cells except in the last stages of vitellogenesis. Follicle cells are characterized by the presence of extensive arrays of rough endoplasmic reticulum (RER) and Golgi complexes and may play a role in vitellogenesis. An ultrastructural analysis of vitellogenesis suggests that oocytes utilize both auto‐ and heterosynthetic mechanisms of yolk formation. Autosynthetsis is suggested by the activity of the Golgi complex and RER, while heterosynthesis is indicated by high levels of endocytotic activity by the oocyte. Follicle cell development and high endocytotic activity in the oocytes may be a reproductive adaptation to accelerate yolk synthesis, resulting in more rapid egg production.
Comparative study of the choanosome of porifera: II. The keratose sponges
Authors: Vacelet Jean , Boury‐Esnault Nicole , De Vos Louis , Donadey Claude
Published: February 2005

The aquiferous system of representatives of the orders Dictyocer‐atida, Dendroceratida, and Verongida has been studied to note its relevance to the systematics of the groups. The volume of the choanocyte chamber, the size and shape of the choanocytes, the number of choanocytes per chamber, the relative development of the mesohyl, and the features of endopinacocytes are estimated from scanning and transmission electron microscopic observations of representatives of most families of the three orders. Although the Dysideidae have a reticulate skeleton and were classified in the order Dictyoceratida, they are actually closer to the Aplysillidae (Dendroceratida) than to dictyoceratids. The anatomy and cytology of the Halisarcidae differ profoundly from those of these three orders and are clearly more closely related to nonkeratose sponges. Some changes in classification lead to a pattern with highly homogeneous orders that clearly differ in their anatomic and cytologic features, which does not support the hypothesis of a common origin of the “keratose” sponges.
Propulsive action of a snake pushing against a single site: Its combined analysis
Authors: Gasc J. P. , Cattaert D. , Chasserat C. , Clarac F.
Published: February 2005

The simultaneous use of electromyography (EMG), strain gauges, and cinematography show that the capacity of continuous displacement from a single peg is based on the following: sequential activity of the tested muscles from front to rear; activity restricted to the short portion of the body in contact with the peg; alternate action of the muscle longissimus dorsi on the two sides, the transition between one side to the other occurring at the site of contact with the peg; unilateral activity of the muscle supracostalis ventralis responsible for a bulging against the peg; a great stability in the direction of the resultant force, which makes only a small angle with the directio of the motion.
Ultrastructural organization of the accessory olfactory bulb of the lizard Podarcis hispanica
Authors: Llahi S. , García‐Verdugo J. M.
Published: February 2005

The ultrastructural organization of the accessory olfactory bulb (AOB) was studied in a squamate reptile, Podarcis hispanica. Five types of neuronal cell bodies were differentiated by their size, location, and ultrastructure. Dark and light small somata were observed in the glomerular layer and correlated with two possible subpopulations of periglomerular cells. Mitral cells, the biggest neurons in the AOB, were preferentially located in the mitral cell layer, but also observed in plexiform layers, and they could be classified into two different types mainly on the basis of the size of their somata. Finally, a fifth neuronal population, the granule cells, were observed in the deepest layers of the AOB.

On the basis of their location and ultrastructure, five different types of synaptic contacts were also observed in the AOB. Vomeronasal nerve terminals made asymmetric synaptic contacts in the glomerular layer. Reciprocal synapses between mitral cell dendrites and granule cell gemmules were identified preferentially in the external plexiform layer, but also in the mitral cell and internal plexiform layers. Terminals forming symmetric synapses on mitral cells were also recognized in the external plexiform layer. In the deepest layers, two types of terminals established asymmetric and symmetric synaptic contacts, respectively, on granule cells.

The basic organization of the AOB of lizards appears rather similar to that of the mammalian olfactory bulb, but some notable differences as to their neuronal composition were found.
Neuronal organization of the accessory olfactory bulb of the lizard Podarcis hispanica: Golgi study
Authors: Llahi S. , García‐Verdugo J. M.
Published: February 2005

The neuronal organization of the accessory olfactory bulb (AOB), which receives sensory information from the vomeronasal organ, was described in a squamate reptile (Podarcis hispanica) by means of light microscopy. Using the Golgi‐impregnation method, seven neuronal types could be distinguished:

Periglomerular cells constitute a morphologically heterogeneous population of small neurons located between and around the glomeruli.

The mitral cells are diffusely distributed in the AOB. Their cell bodies are usually located within the mitral cell layer, but some of them could be also observed in the plexiform layers. Mitral cells were classified into three subgroups on the basis of their sizes and dendritic tree morphologies. Thus, the “outer mitral cells” have the biggest cell bodies, and their distal secondary dendrites are mainly distributed rostrocaudally in the external plexiform layer. The “inner mitral cells” have large cell bodies, and their secondary dendrites are distributed dorsoventrally and are located deeper than those of the other two subgroups. The third type, the “small mitral cells,” is the smallest one among mitral cells in the AOB, and from their cell bodies, only two main dendritic trunks arise.

The granule cells are composed of several categories based on their different cell body locations and dendritic tree morphologies. Thus, the “superficial granule cells” are located exclusively in the external plexiform layer and have small dendritic fields. The “middle granule cells” have fusiform cell bodies—situated in the internal plexiform layer—and present a wide dendritic projection area. Finally, the “deep granule cells” are distributed throughout the granule cell layer and include a great variety of dendritic tree morphologies.

The distribution and morphological features of all neuronal types constituting the AOB of Podarcis were compared with those reported on other vertebrates. The results suggest that the lamination pattern and neuronal organization of the AOB in lizards are more similar to that of mammals than to that of the remaining vertebrates.
Microscopic study of the pyloric caeca of the starfish Marthasterias glacialis (Echinodermata): Finding of endocrine cells
Authors: Martinez A. , Villaro A. C. , Sesma P.
Published: February 2005

The ultrastructure of five epithelial cellular types is described. (1) Absorptive‐storing cells possess a striated border and accumulate lipids and glycogen. They also contain an apical multivesicular complex and numerous membrane‐bound PAS‐positive granules of unknown significance. (2) Zymogenic cells contain numerous, large secretory granules. These cells also possess microvilli and accumulate lipid droplets. (3) Current‐producing cells contain bundles of thick and thin myofilaments and extend from the basal lamina to the lumen. (4) Mucous cells display the characteristic features of such secretory cells. (5) In addition to these four cellular types, already observed under the light microscope by other authors, endocrine cells have also been identified by both light and electron microscope. They contain variable amounts of secretory granules of diverse sizes and electron densities. Immunocytochemical studies reveal the presence of cells immunoreactive to somatostatin, glucagon, and pancreatic polypeptide. Intraepithelial nerve fibers in contact with endocrine cells are also present. As far as we know, this appears to be the first description of enteroendocrine cells in the phylum Echinodermata.
Obplacental giant cells of the domestic rabbit: Development, morphology, and intermediate filament composition
Authors: Blackburn Daniel G. , Osteen Kevin G. , Winfrey Virginia P. , Hoffman Loren H.
Published: February 2005

Obplacental giant cells are large (210 m̈m) polyploid cells that appear in the stroma of the pregnant uterus of the rabbit following ovoimplantation. Histological examination of a complete developmental series indicates that obplacental giant cells arise from trophoblastic knobs that have traversed the uterine epithelium during early implantation. During maturation, the cells undergo a massive (approximately 6,000%) increase in volume and penetrate deeply into the uterine stroma and myometrium, where they often become associated with blood vessels and smooth muscle cells. Giant cells at mid‐gestation contain one or two large nuclei with prominent nucleoli and appear to be amitotic. They are rich in Golgi complexes, RER, SER, and cortically distributed cytoplasmic filaments, and contain intracellular canaliculi lined by microvilli. Giant cells vary with respect to the occurrence of lipid droplets, phagocytotic inclusions, lysosomal structures, and electron‐dense granules. Immunocytochemistry demonstrates that the giant cells exhibit intermediate filaments related to cytokeratin and vimentin, but are negative for desmin and for an endothelial cell marker, Factor VIII‐related antigen. The cells are positive for cytokeratin from their inception, but only become vimentin‐positive between Days 12 and 15 of pregnancy, a change seemingly related to their detachment from epithelial tissue to take on an independent existence. Our findings indicate that the giant cells originate from obplacental trophoblast and, at maturity, exhibit cytoskeletal characteristics of isolated epithelial cells, as well as a complement of organelles suggestive of synthetic activity.
Differentiation of the inner ear sensory epithelia of Proteus anguinus (Urodela, amphibia)
Authors: Bulog Boris
Published: February 2005

The stages of differentiation of the inner ear sensory epithelia of the neotenous cave urodele, Proteus anguinus, was studied with light and electron microscopy. Comparative ultrastructural analysis among specimens of different sizes confirms that new sensory cells may be generated throughout life, particularly along the periphery of the saccular macula. The inner ear of Proteus contains at least four types of sensory cells that differ in their apical ciliary part.

The lungs and air‐filled buccal cavity may function as transducers of sound pressure in underwater conditions. Sound waves might be transmitted from the buccal cavity to the connected oval window. The very complex orientation of the sensory hair cells of the saccular macula and the large overlying saccular otoconial mass suggest that this macula facilitates orientation of Proteus in its underground aqueous habitat.
Centers of mass and weight distribution in spiders of the family uloboridae
Authors: Opell Brent D.
Published: February 2005

In the Uloboridae, web reduction is accompanied by changes in opisthosomal shape, leg length, and web‐monitoring tactics. These morphological changes make reduced‐web spiders more cryptic and alter their leg leverage and centers of mass. When compared with the orb‐weaver Uloborus glomosus, the irregular, reduced‐web spider, Miagrammopes animotus, invests more mass in its prosoma and first legs. However, the latter species' elongate opisthosoma posteriorly shifts this region's center of mass, causing the relative position of its composite center of mass and the distribution of weight between its first and fourth legs to be similar to that of the orb‐weaver. Like these species, the opisthosomal center of mass of the triangle‐weaver, Hyptiotes cavatus, lies near its midpoint. However, the shorter first legs and rounder, heavier opisthosoma of Hyptiotes posteriorly shift its composite center of mass and distribute more of its weight onto its fourth legs. Consequently, the morphology of M. animotus can be adequately explained by its adaptiveness for web manipulation, balance, and weight distribution and the crypsis that these features confer as an ancillary advantage. In contrast, anatomical changes in H. cavatus are better explained as adaptations for web manipulation and crypsis.
Developmental morphology of the solum nasi in the mouse lemur (Microcebus murinus)
Authors: Lozanoff Scott , Diewert Virginia M.
Published: February 2005

The solum nasi of Microcebus murinus is characterized by the presence of a zona annularis, continuity between the anterior transverse lamina and the paraseptal cartilage, a continuous paraseptal cartilage, a palatine cartilage and a posterior transverse lamina. It lacks a fibula reuniens and possibly a cartilage of the nasopalatine duct as well as a palatine papillary cartilage. The morphology in M. murinus closely resembles that seen in Tupaia and Galago. This affinity results from the retention of primitive traits. However, Galago is reported to lack a zona annularis, thus displaying a specialization not shared with M. murinus. Therefore, the zona annularis provides a useful trait for distinguishing between the ontogenies of M. murinus and Galago.
Phylogenetic diversity of cellular organization in the cardia of muscoid flies (diptera: Schizophora)
Authors: King David G.
Published: February 2005

In each of 30 dipteran species, representing 13 acalyptrate and 7 calyptrate families, the cardia is formed from specialized cells at the junction between foregut and midgut. Foregut epithelium forms the stomodeal valve; midgut epithelium envelops the valve to form the cardia's outer wall. Cytological characteristics within these epithelia differ from region to region and from species to species. Since the cardia secretes the peritrophic membrane, cardias with diverse patterns of cellular differentiation may be expected to produce peritrophic membranes with similarly diverse properties. Close relatives often share more details of cardia structure than do distantly related taxa. Within the monophyletic Calyptratae, a common pattern of cellular differentiation includes three distinct zones of columnar midgut cells enclosing a flanged stomodeal valve. Among species in the paraphyletic Acalyptratae, midgut typically includes a single zone of tall columnar cells, while the valve may be spheroidal, cylindrical, conical, or flanged. The correlation of phylogenetic distance with divergence in cardia organization implies a strong influence of ancestry upon current structure, regardless of current diet. However, at least some of the observed diversity in cardia structure is associated with dietary divergence. Calyptrate flies with derived blood‐feeding behavior display cellular differentiation that is simplified from that seen in calyptrate relatives with less specialized feeding habits. This evolutionary modification suggests that cardia organization and hence peritrophic membrane structure can adapt to dietary changes, with possible significance for the spatial organization of digestive processes and interactions with ingested microorganisms.
Erythropoietic bone marrow in the pigeon: Development of its distribution and volume during growth and pneumatization of bones
Authors: Schepelmann Karsten
Published: February 2005

During postnatal development of the pigeon, a large portion of the skeleton becomes pneumatized, displacing the hemopoietic bone marrow. The consequences of pneumatization on distribution and quantity of bone marrow as well as the availability of other sites for hemopoiesis have been investigated. Hemopoietic marrow of differently aged pigeons divided into five groups from 1 week posthatching (p.h.) up to 6 months p.h. was labeled with Fe‐59 and examined by serial whole‐body sections. Autoradiography and morphometry as well as scintillation counts of single bones and organs were also carried out. No sign of a reactivation of embryonic sites of erythropoiesis was found. Bone marrow weight and its proportion of whole‐body weight increased during the first 4 weeks p.h. from 0.54% to 2.44% and decreased in the following months to about 1.0%. The developing bone marrow showed a progressive distribution during the first months of life, eventually being distributed proportionally over the entire skeleton, except for the skull. At the age of 6 months p.h. bone marrow had been displaced, its volume decreasing in correlation to increasing pneumaticity and conversion to fatty marrow. This generates the characteristic pattern of bone marrow distribution in adult pigeons, which shows hemopoietic bone marrow in ulna, radius, femur, tibiotarsus, scapula, furcula, and the caudal vertebrae.
Dermal extracellular lipid in birds
Authors: Stromberg M. W. , Hinsman E. J. , Hullinger R. L.
Published: February 2005

A light and electron microscopic study of the skin of domestic chickens, seagulls, and antarctic penguins revealed abundant extracellular dermal lipid and intracellular epidermal lipid. Dermal lipid appeared ultrastructurally as extracellular droplets varying from less than 1 μm to more than 25 μm in diameter. The droplets were often irregularly contoured, sometimes round, and of relatively low electron density. Processes of fibrocytes were often seen in contact with extracellular lipid droplets. Sometimes a portion of such a droplet was missing, and this missing part appeared to have been “digested away” by the cell process. In places where cells or cell processes are in contact with fat droplets, there are sometimes extracellular membranous whorls or fragments which have been associated with the presence of fatty acids. Occasionally (in the comb) free fat particles were seen in intimate contact with extravasated erythrocytes. Fat droplets were seen in the lumen of small dermal blood and lymph vessels. We suggest that the dermal extracellular lipid originates in the adipocyte layer and following hydrolysis the free fatty acids diffuse into the epidermis. Here they become the raw material for forming the abundant neutral lipid contained in many of the epidermal cells of both birds and dolphins. The heretofore unreported presence and apparently normal utilization of abundant extracellular lipid in birds, as well as the presence of relatively large droplets of neutral lipid in dermal vessels, pose questions which require a thorough reappraisal of present concepts of the ways in which fat is distributed and utilized in the body.
External morphology of the antennae of Damalinia ovis (phthiraptera: Trichodectidae)
Authors: Clarke Anthony R.
Published: February 2005

The antennae of adult Damalinia ovis, the sheep louse, were studied using light and scanning electron microscopy. Sensory structures are located on all three antennal segments with the predominant sensilla type being tactile. Nine different types of sensilla are described on the basis of external appearance. One of the sensilla, designated a “pit organ” because of its unusual shape, has not been described previously. A pair of these sensilla are present on each antenna, and their function is unknown. A group of 11 sensilla on the tip of each antenna contains olfactory and chemosensory pegs, and a possible thermohygroreceptor. The antennae are sexually dimorphic, the male having more tactile sensilla, two well‐developed terminal hooks, and a different cuticular architecture on the posterior surface of antennal segment 1.
Screening pigment granule formation in Eumesosoma roeweri (Arachnida: Opiliones)
Authors: Johnson J. Kelly , Gordon William C.
Published: February 2005

A unique pathway that utilizes endoplasmic reticulum (ER) networks is proposed for screening pigment granule formation in the retina of adult Eumesosoma roeweri. Smooth endoplasmic reticulum (SER) functions to transport pigment particles to the formative site. Each site is composed of concentric, interconnected rings of SER that are filled with dense‐cored, spherical pigment particles. Formation of the screening pigment granule begins by the release of particles from the innermost rings of carrier SER. Continued release followed by fusion and condensation of the pigment particles results in the formation of a mature pigment granule.
An electron microscopic study of the development of amphioxus, Branchiostoma belcheri tsingtauense: Cleavage
Authors: Hirakow R. , Kajita N.
Published: February 2005

Development of the Asian amphioxus, Branchiostoma belcheri tsingtauense, was investigated by scanning and transmission electron microscopy (SEM and TEM) from the fertilized egg through the blastula stage. The fertilized egg is spherical (mean diameter 115 μm after SEM preparation) and is covered with microvilli. Throughout cleavage, the second polar body remains attached to the animal pole. The cleavage type in this species is essentially radial, as revealed by SEM observations. At the third cleavage or 8‐cell stage, and at later stages, a size difference between blastomeres in the animal and the vegetal halves is clearly discernible, but less marked than that reported for the European amphioxus, B. lanceolatum. During the period spanning the third to the fifth cleavage (8–32‐cell) stages, blastomeres are arranged in tiers along the animal‐vegetal axis. After the sixth cleavage, or 64‐cell stage, the tiered arrangement of the blastomeres is no longer seen. At the 4‐cell stage, the blastocoel or cleavage cavity is seen as an intercellular space, opening to the outside. The blastocoel remains open at the animal and the vegetal poles in later stages. Throughout early development, the cytoplasm of the blastomeres includes yolk granules, mitochondria, Golgi complexes, and rough and smooth endoplasmic reticulum. Chromatin in the interphase nucleus is not clearly demonstrated, and chromosomes in the mitotic phase are also extremely difficult to detect. As yet, regional differences have not been found in distribution and organization of cytoplasmic components with respect to prospective ectodermal, mesodermal, and endodermal areas in the fertilized egg and later cleaved embryos, although there are possibly fewer yolk granules in the region of the animal pole than in the vegetal polar zone.
Lectin histochemistry of the hyaline layer in the asteroid, pisaster ochraceus
Authors: Reimer Corinne L. , Crawford Bruce J.
Published: February 2005

Six different lectins were used to study the carbohydrate nature of the hyaline layer (HL), the external extracellular matrix of the starfish embryo. Thin sections of embryos fixed in the late gastrula stage were incubated with five fluoresceinated lectins: Con A, WGA, RCA, UEA‐I, and SBA. All but UEA‐I labelled the HL, suggesting that the following sugars are present: mannose and/or glucose, glcNAc and/or Neu5Ac, galactose, and galNAc. The different lectins produced variable degrees of labelling, with WGA, RCA, and SBA producing more intense labelling than Con A. Binding of lectins by the HL was studied at the ultrastructural level by exposing ultrathin sections to the following lectin‐gold conjugates: Con A, WGA, PNA, SBA, and LFA. Lectin binding was observed over the various regions of the HL, recognized by Crawford and Abed (J. Morphol. 176:235–246, '86), i.e., the intervillus layer, the supporting layer and the coarse outer meshwork. Local differences in labelling patterns were observed among the various lectins, with SBA labelling all regions intensely, WGA and PNA labelling the supporting layer predominantly, and Con A labelling the HL only lightly. No labelling was observed with LFA. These lectin‐labelling patterns in the HL demonstrate the presence of different glycoconjugates in different regions of the HL, suggesting that the layers differ biochemically. The existence of biochemical differences strengthens the idea that each layer may have different functions in the developing starfish embryo.
Videofluorographic analysis of tongue movement in the rabbit (Oryctolagus cuniculus)
Authors: Cortopassi David , Muhl Zane F.
Published: February 2005

The movement of the entire tongue and intermolar eminence during mastication is described in the domestic rabbit (Oryctolagus cuniculus). Tongue movement and jaw position were analyzed videofiuorographically from separate lateral and dorso‐ventral views in six rabbits. Metallic markers were inserted into the tongue so that its movement was visible on the fluorographic image. Frame‐by‐frame analysis of the videofluorographic tape recordings demonstrates that tongue movement in all animals was identical in direction during each part of the chewing cycle. In the lateral view the forepart of the tongue moves down and forward during the opening stroke, whereas the intermolar eminence moves up and forward to appose the palate. During the closing stroke, as the tip of the tongue moves up and back, the intermolar eminence lowers from the palate and retracts. During the power stroke the forepart of the tongue is at its most elevated and retruded position, while the intermolar eminence is its lowest and most retruded. The dorso‐ventral view showed that lateral movement of the tongue and mandible are highly synchronous. The intermolar eminence decreases in width during the power stroke, possibly twisting to place or keep food on the teeth. An anterior to posterior undulating movement of the entire tongue occurs throughout the chewing cycle. As the intermolar eminence elevates to appose the palate during the opening stroke, it may replace the bolus on the teeth on the chewing side. The intermolar eminence also appears to be twisting during the closing and power strokes to place or maintain food on the teeth.
Morphological changes in the oocyte and its surrounding vestments during in vivo fertilization in the dasyurid marsupial sminthopsis crassicaudata
Authors: Breed W. G. , Leigh C. M.
Published: February 2005

This light and transmission electron microscopical study shows that the first polar body is given off before ovulation and that part of its cell membrane and that of the surrounding oocyte have long microvilli at the time of its ejection. Several layers of cumulus cells initially surround the secondary oocyte and first polar body, but the ovulated oocytes in the oviducts in the process of being fertilized do not have cumulus cells around them. Partly expelled second polar bodies occur in the oviduct; they are elongated structures that lack organelles and have electron‐dense nuclei. A small fertilization cone appears to form around the sperm tail at the time of sperm entry into the egg and an incorporation cone develops around the sperm head in the egg cytoplasm. In three fertilized eggs a small hole was seen in the zona, which was presumably formed by the spermatozoon during penetration. Cortical granules, present in ovarian oocytes, are not seen in fertilized tubal or uterine eggs; release of their contents probably reduces the chances of polyspermy, although at least one polyspermic fertilized egg was seen and several other fertilized eggs had spermatozoa within the zona pellucida. In the zygote the pronuclei come to lie close together, but there was no evidence of fusion. A “yolk mass,” which becomes eccentric before ovulation, is extruded by the time the two‐cell embryos are formed, but many vacuoles remain in the non‐yolky pole of the egg. A shell membrane of variable thickness is present around all uterine eggs but its origin remains undetermined.
Ultrastructure of the oviduct of the lung fluke, paragonimus ohirai (Trematoda: Troglotrematidae)
Authors: Orido Yasuhide
Published: February 2005

The oviduct of Paragonimus ohirai is lined by an epithelium composed of cells that rest on a prominent basal lamina and exhibit extensive basal infoldings. Apical surfaces of the epithelial cells are lamellated, and height and abundance of lamellae vary in different regions. Cilia are confined to two separate areas and are variable with respect to their axonemal pattern. There are five principal regions of the oviduct: infundibular (IR), distal ciliary (DCR), preseminal receptacle (PSR), proximal ciliary (PCR), and junctional (JR). The pattern of organization of cytoplasmic organelles such as mitochondria, Golgi complexes, and lysosomes is distinctive within each region. The remainder of the wall consists of circularly arranged myofiber bundles, together with a plexus of nerve fibers. The structure of the oviduct in relation to passage of oocytes, movement of spermatozoa, and fertilization is discussed.
Comparative analysis of the neck region in spermatids and spermatozoa of some orthopteran insects
Authors: Guerra R. , Carballada R. , Esponda P.
Published: February 2005

The ultrastructure of the neck region and the participation of noncovalent and disulphide bonds in the head–tail attachment were analyzed in spermatids and spermatozoa of some orthopteran species from the families Tettigoniidae and Acrididae. This study combined conventional electron microscopy with cytochemical procedures to detect acidic proteins and lysine‐rich basic proteins, and with treatments using the disruptive agents sodium dodecyl sulfate (SDS) and dithiothreitol (DTT). The organization of the neck region differs in spermatozoa among species in the families analyzed. In Acrididae the neck consists of the beginning of the axoneme attached to the nuclear envelope and surrounded by the centriolar adjunct material. Tettigoniidae species possess a complex organization in the form of a laminar “connective piece,” which shows a high content of lysine‐rich and acidic proteins. Experiments using SDS and DTT demonstrate that in Acrididae the head–tail connection is strong, with both noncovalent and disulphide bonds important in maintenance of the attachment. In Tettigoniidae, however, despite the presence of a morphologically well organized connective piece, the head‐tail attachment is biochemically labile in comparison to that of Acrididae. The relationships between the morphology of these neck structures and their stability mediated by noncovalent and/or disulphide bonds are discussed.