bluuebunny/crossref_metadata_2025 huggingface dataset:
Metamorphic changes in the intestine of three species of lampreys
Authors: Hilliard R. W. , Bird D. J. , Potter I. C.
Published: February 2005

Measurements have been made of those changes which lead to increases in the surface area of the intestine during the metamorphosis of three species of lampreys. Although the intestine of the Southern Hemisphere lamprey, Geotria australis, increases in length by 1.13 times and in diameter by 1.12 times, the main factor influencing the 5.71 times increase in surface area is the development of longitudinal folds. The contribution of the typhlosole to the internal perimeter of the intestine is less in most life cycle stages of G. australis than in Lampetra spp. The changes in the various intestinal measurements of the nonparasitic species L. planeri parallel those of the presumed ancestral parasitic species, L. fluviatilis, during the first six stages of metamorphosis. However, the longitudinal folds, but not the typhlosole, subsequently start regressing in L. planeri just after the time when the rate of gonadal development increases markedly. An account is also given of the pattern of fold formation and the development of the typhlosolar vein in G. australis.
A fine structural study of metamorphosis of the hydrozoan Mitrocomella polydiademata
Authors: Martin Vicki , Chia Fu‐Shiang , Koss Ron
Published: February 2005

This report is a comprehensive fine structural analysis of the morphological changes occurring during metamorphosis of the marine hydrozoan Mitrocomella polydiademata. Five stages are recognized during metamorphosis: planulae just prior to settlement, ball and filiform stages, immature polyps, and primary feeding polyps. Settlement and metamorphosis of cnidarian planulae involve such changes as ciliary arrest, discharge of nematocytes, secretion of glandular cells, differentiation of cells, and changes in cell and body shape.
Embryonic development of the alimentary canal and ectodermal derivatives in the primitive moth,Neomicropteryx nipponensisissiki (Lepidoptera, Micropterygidae)
Authors: Kobayashi Yukimasa , Ando Hiroshi
Published: February 2005

The formation of the alimentary canal, nervous system, and of other ectodermal derivatives in the embryo of the primitive moth,Neomicropteryx nipponensisIssiki, is described. The stomodaeum is formed from an invagination in the medioposterior portion of the protocephalon. The proctodaeum arises as an extension of the amnioproctodaeal cavity. The midgut epithelium orginates from anterior and posterior rudiments in blind ends of the stomodaeum and proctodaeum. The decondary dorsal organ is formed in developing midgut. The development of the brain is typical of insects. The ventral nerve cord originates in large part from neuroblasts arising in 3 gnathal, 3 thoracic, and 11 abdominal segments. Intrasegmental median cord cells probably differentiate into both ganglion cells and glial elements of the ventral nerve cord; intersegmental cells appear not to participate in the formation of the nervous system. The stomatogastric nervous system develops from three evaginations in the dorsal wall of the stomodaeum, and consists of the frontal, hypocerebral, and ventricular ganglia, the recurrent nerve, and corpora cardiaca. Five stemmata arise from the epidermis on each side of the head. Five pairs of ectodermal invaginations are formed in the cephalognathal region to produce the tentorium, mandibular apodemes, corpora allata, and silk glands. Prothoracic glands orginate in the prothorax. Mesothoracic spiracles shift anteriorly to the prothorax during development. Oenocytes arise in the first seven abdominal segments. Invaginated pleuropodia are formed in the first abdominal segment.
The cocoon‐producing cells of Eisenia foetida (Annelida, Oligochaeta): A histochemical and ultrastructural study
Authors: Morris G. M.
Published: February 2005

Type 1 cells of the clitellar epithelium of Eisenia foetida secrete a protein resembling keratin in histochemical reaction. Ultrastructurally, type 1 cells are characterized by membrane‐bound, pockmarked granules ranging in diameter from 1.0 to 3.0 μm. Immature granules often exhibit an orgnized microfibrillar substructure. Individual microfibrils are 17 ± 1 nm in diameter. Type 2 cell secretion contains protein, nonsulfated acid mucosubstance, and neutral mucosubstance with 1,2‐glycol groups. The coarsely fibrillar granules are membrane bound and vary in diameter from 0.5 to 1.0 μm. The necks of both type 1 and type 2 cells contain a peripheral ring of microtubules, 20 ± 1 nm in diameter.
Size and shape of the mandibular condyle in primates
Authors: Smith Richard J. , Petersen Carl E. , Gipe David P.
Published: February 2005

The relationships between the size of the articular surface of the mandibular condyle and masticatory muscle size, tooth size, diet, and biomechanical variables associated with mastication were studied by taking 12 measurements on skulls of 253 adult female anthropoid primates, including three to ten specimens from each of 32 species.

In regressions of condylar length, width, or area against body weight, logarithmic transformations substantially improve the fit of the equations compared with untransformed data. There is a strong relationship betwden condylar measurements and body weight, with all correlations being .94 or higher. The slopes of the allometric regressions of length, width, and area of the condylar head indicate slight positive allometry with body size.

Folivorous primates have smaller condyles than frugivorous primates, and colobines have smaller condyles than cebids, cercopithecines, or hominoids. When colobines are eliminated, the differences between frugivores and folivores are not significant. However, the two species with the relatively largest condyles are Pongo pygmaeus and Cercocebus torquatus, suggesting that there may be a relationship between unusually large condylar dimensions and the ability to crak hard nuts between the teeth.

Cranial features having strong positive correlations with condylar dimensions include facial prognathism, maxillary incisor size, maxillar postcanine area, mandibular ramus breadth, and temporal fossa area. These data are interpreted as indicating that relatively large condyles are associated with relatively large masticatory muscles, relatively inefficient mandibular biomechanics, and a large dentition. These relationships support the growing evidence that the temporomandibular joint is a stress‐bearing joint in normal function.
Skeletal muscle‐smooth muscle interaction: An unusual myoelastic system
Authors: Hikida Robert S. , Peterson Wesley J.
Published: February 2005

The serratus superficailis metapatagialis (SSM) of pigeons is a skeletal muscle with unusual properties. It lies between the ribs and the trailing edge of the wing, where it is attached to the skin by a system of smooth muscles having elastic tendons. Wing movements during flight induce marked changes in this muscle's length. The SSM inserts onto the deep fascia, and at its termination the skeletal muscle contains large numbers of microtubules. Many myofibrils attach to leptomeric organelles, which then attach to the terminal end of the skeletal muscle fiber. The deep fascia next connects to the dermis of the skin by bundles of smooth muscles that have elastic tendons at both ends. This system allows large movements of the muscle while preventing its fibers from overstretching. The movements and presumed forces acting at this muscle make the presence of sensory receptors such as muscle spindles unlikely. Spindles are absent in this muscle.
Functional and morphological bases of trophic specialization in sunfishes (Teleostei, centrarchidae)
Authors: Lauder George V.
Published: February 2005

The gross morphology and electrical activity of the muscles of the pharyngeal apparatus of centrarchid sunfishes (Lepomis) are analyzed within a monophyletic clade containing species specialized for snail‐eating. Outgroup comparisons of both structure and activity patterns of muscles permit examination of the relationship between specialized diet and function of the trophic apparatus. In most sunfish species, electrical activity in the pharyngocleithralis internus muscle significantly overlaps that in the retractor dorsalis muscle during pharyngeal transport, indicating that the upper and lower pharyngeal jaws retract together. Activity in the pharyngohyoideus, levatores externi, and levator posterior also significantly overlaps activity of the retractor dorsalis.

Snail‐eating is associated with derived morphological, behavioral, and functional features. The shell is crushed before pharyngeal transport, correlated with extensive overlap in activity periods of muscles. One species, Lepomis microlophus, possesses a highly stereotyped neuromuscular repertoire that does not vary with prey type. All prey, even fish and worms, are subjected to crushing. Lepomis gibbosus exhibits the crushing pattern of muscle activity only when feeding on snails. L. microlophus has a hypertrophied levator posterior muscle, but the lines of action of the pharyngeal muscles are similar to the primitive condition. Pharyngeal transport in this species is unique in that activity of the pharyngocleithralis internus alternates with that of the retractor dorsalis.

In sunfishes, alterations in the central control of peripheral structures have produced major changes in the sequence in which homologous components of the structural network are activated.
The exocrine glands of the male of Eldana saccharina walker (Lepidoptera, galleriinae): Intervention in precopulatory behavior
Authors: Farine Jean‐Pierre
Published: February 2005

The scent apparatus of male Eldana saccharina is a glandular complex on the costal area of the forewing. It consists of two parts; glandular complex 1 is composed of five kinds of cells (epidermal cells, scale cells, glandular cells, supporting cells, duct cells); glandular complex 2 also shows five types of cells (epidermal cells, scale cells, glandular cells, duct cells, trichogen cells). The secretory products of the two parts are discharged into separate ducts which converge before opening onto the lower side of the wing. The male also has two prominent hair‐pencils borne on the coremata and large secretory trichogen cells on the genital valves. Each of these exocrine gland components plays an important part in formation of the chemically complex pheromones utilized in the precopulatory behavior of the male.
The ultrastructure of the blood cells of the pike Esox lucius L.
Authors: Savage A. G.
Published: February 2005

The ultrastructure of pike peripheral blood cells, lymphocytes, thrombocytes, granulocytes, and monocytes is described. At present there are no reliable criteria for differentiating between round thrombocytes and small lymphocytes of fish on a routine basis. At the ultrastructural level thrombocytes could be clearly differentiated from lymphocytes by cytoplasmic canals and vesicles, marginal microtubules, and large glycogen deposits. Electron microscopic identification of thrombocytes was confirmed by examining the ultrastructural features of a purified thrombocyte fraction. In addition, a preliminary investigation of the structure of the haemopoietic cells in the thymus, anterior kidney, and spleen was carried out.
Developmental stages of ovarian follicles of the silkworm, Bombyx mori L
Authors: Yamauchi Hideo , Yoshitake Narumi
Published: February 2005

Oogenesis in the silkworm, Bombyx mori, was studied by light and electron microscopy of sections of resin‐embedded follicles. The development of the follicles was divided into a series of 12 distinctive stages based on various morphological criteria. Structural changes in the oocyte, nurse cells, and follicle cells are described and illustrated.
Freeze‐fracture characteristics of insect gustatory and olfactory sensilla. II. Cuticular features
Authors: van der Wolk Fran M. , Menco B. Ph. M. , Van Der Starre H.
Published: February 2005

The freeze‐fracture technique has been used to obtain detailed information about cuticular constituents and outgrowths of the external skeleton of labella and antennae in the bluebottle fly Calliphora vicina and the antennae of the small moth (Yponomeuta spp.). The lamellated exoskeleton has a fibrous endocuticle and an exocuticle lacking fibers. Ductuli connecting the inside of the animal with the outside run perpendicularly through the endocutile and at angles of up to 45° in the exocuticle. Skeletal outgrowths lack fibers and display fracture features similar to those of the exocuticle. Among those having neuronal endings, gustatory, olfactory, and tactile hairs can be recognized. Noninnervated outgrowths can be subdivided into scales and pseudotrichia. Criteria such as shape, length/width‐ratio of hairs, texture, presence and place of pores, shape of pores, and form of the socket or base are presented for further classification. Cuticular features of single‐walled olfactory hairs of Calliphora are compared with those of several other species. Based on the shape of the pores, five types of hairs can be distinguished using literature data. It is concluded that the freeze‐fracture technique is a valuable tool with which to describe the microarchitecture of the insect exoskeleton and supplements scanning electron microscopy, which is useful for describing the overall skeletal features.
The external morphology of contact‐chemoreceptive hairs of flies and the motility of the tips of these hairs
Authors: van der Wolk Fran M. , Koerten H. K. , van der Starre H.
Published: February 2005

The external morphology of contact‐chemoreceptive hairs (taste hairs) of six fly species, Calliphora vicina, Lucilia caesar, Musca domestica, Phormia terranovae, Sarcophaga carnaria and Stomoxys calcitrans, is described. The species can be distinguished by the differences between the patterns of taste hairs at the ventral side of their prothoracic tarsi. Taste hairs can be subdivided into morphological types, using the shape of the cuticle around the apical pore as criterion, even though this shape changes slightly on opening and closing of the pore. Light microscopical studies reveal that the nature and osmolarity of stimuli are decisive for the effect stimuli have on the shape of the top of the labellar hairs. The motions of the apical cuticle appear to be reversible.

Gentle ultrasonic treatment preserves the shape of the cuticle of the top and the diameter of the pores on fluid stimulation. This technique makes it possible to study the effect of a previous stimulation on both tarsal and labellar hairs with the scanning electron microscope. It is supposed that stimuli can affect cuticular components around the pore, producing volume changes in that cuticle which alter the diameter of the pore.
Ultrastructure of the neuromuscular system of the polyp of Aurelia aurita L., 1758 (Cnidaria, scyphozoa)
Authors: Chia Fu‐Shiang , Amerongen Helen M. , Peteya Daniel J.
Published: February 2005

Fine structural study indicates that the neuromuscular system of stage I polyps of Aurelia aurita is exclusively ectodermal.

The three major muscle fields are the radial muscles of the oral disc, the longitudinal muscles of the tentacles, and the muscle cords of the septae and the column; the muscle fields are in physical continuity at the peristomial pits and share a common innervation and type of myofibril. The myofibril is striated in the tentacle base, in the outer oral disc, and in the upper part of the muscle cord; it grades into a smooth muscle toward the tentacle tip, the mouth, and the lower part of the cord. There is a fourth field of longitudinal smooth muscle in the pharynx.

The nervous system consists of an epithelial sensory cell in the tentacle and a single type of neuron found in the subepithelial layer of the tentacle, oral disc, and muscle cord. The lack of gap junctions suggests that there is no nonnervous conduction system. The subepithelial layer also contains three types of fibers and a type of soma which cannot be characterized as neuronal. The soma is identified as the “neurosecretory cell” described in Chrysaora. The absence of neuromuscular elements in the column and stolon distinguishes the Aurelia aurita collected from Washington, USA, from English polyps previously described.
The structure and function of the bursa copulatrix of the monarch butterfly (Danaus plexippus)
Authors: Rogers Steffen H. , Wells Harrington
Published: February 2005

The bursa compulatrix of the Monarch butterfly was investigated utilizing light microscopy, histochemistry, and scanning and transmission electron microscopy in order to relate its morphology to the release of sperm from the spermatophore. The bursa has a row of large chitinous teeth on either side of the organ. The dorsal and ventral surfaces are covered with chitinous plates, the plates having bristles on one side. A single layer of cells lies under both the plates and teeth, one columnar cell under each plate, one cuboidal cell under each tooth. The toothed area has no muscle cells. However, the dorsal and ventral hemispheres of the bursa each have a crescent‐shaped packet of muscle fibers that traverse the organ; there are no longitudinal fibers. Spermatophores with thick walls were found in the bursal lumen. Morphological evidence suggests that the presence of the spermatophores is sensed by the bristles and that the packets are opened by contraction of the muscles bringing the large teeth into contact with the spermatophore wall.
Functional adaptations of the digestive system of the carnivorous mollusc Pleurobranchaea californica MacFarland, 1966
Authors: Morse M. Patricia
Published: February 2005

The opisthobranch mollusc Pleurobranchaea californica feeds on whole organisms and the functional morphology of the digestive system reflects this behavior. By a rhythmic behavior involving well‐developed extrinsic buccal muscles and hemocoelic fluid, the buccal mass is protracted to the tip of the everted oral tube. Here a series of repeated protractions and retractions of the intrinsic buccal muscles associated with the flat radular ribbon and jaws draws the prey into the buccal cavity and conveys it to the dorsal esophagus, where by peristaltic action it is passed to the expansible crop for storage. Prey entering the buccal cavity is mixed with acid from a large single gland and secretion from the paired salivary glands. Prey is retained in the crop over long periods of time while it is slowly broken down and passed via the stomach into the digestive glands. Special modifications that allow flexibility of the digestive organs include elongated salivary gland ducts with propulsive bulbs, long flexible nerve cords connecting the ganglia, a long, large muscular duct for storage of the acid secretion, large jaws for muscle attachment and grasping the prey, and a broad radular ribbon with many teeth that acts as a conveyor belt to move food. Additional modifications for handling whole prey include a buccal membrane that aids in maintaining hemocoelic fluid pressure, the extensive acid gland for immobilization of prey, and the expansible crop for storage of food.
Histomorophological studies of the female reproductive system of Platynotus punctatipennis (Coleoptera: Tenebrionidae)
Authors: Inamdar Ruta R. , Joshi P. V.
Published: February 2005

The internal reproductive apparatus of female Platynotus punctatipennis is composed of the paired ovaries, paired lateral oviducts, common oviduct, spermatheca associated with its accessory gland, and a bursa copulatrix. The accessory (colleterial) glands are absent. The ovary is made up of a large number of telotrophic ovarioles which are covered by a double‐layered peritoneal sheath. The terminal filament is separated from the germarium by the basement membrane of the latter and consists of a syncytial core surrounded by the peritoneal sheath. Nutritive cords are absent. The pedicel shows highly eosinophilic and PAS‐positive secretion of obscure origin. The spermatheca reveals a number of interesting features. It is composed of a pair of sperm‐storing tubules, enclosed in a very thin muscle layer. A winecup‐like structure, provided with a thick coat of circular muscles, connects the spermathecal gland with thespermathecal duct. Four types of intimal linings occur in the spermatheca and its associated structures. The wine‐cup‐like connection and four types of intima are entirely new features observed. Histology of the various parts of the reproductive apparatus is described.
Synganglial and neurosecretory morphology of the chicken mite Dermanyssus gallinae (DeGeer) (Mesostigmata: Dermanyssidae)
Authors: Severino G. , Oliver J. H. , Pound J. M.
Published: February 2005

Histological techniques and paraldehyde‐fuchsin (PAF) staining were used to study the synganglion and to locate neurosecretory regions and neurosecretion within the synganglion of the chicken mite, Dermanyssus gallinae. The synganglion, which is formed internally by neuropilar ganglia, gives rise to a single esophageal and paired cheliceral, palpal, pedal (I‐IV), and opisthosomal nerves. The neuropilar ganglia are interconnected by commissures and connectives within the synganglion. Twelve PAF‐positive neurosecretory regions are present in unfed protonymphs, unfed deutonymphs, virgin males and females, and mated males. There are 11 PAF‐positive neurosecretory regions in larvae, 24–72 hours post‐fed deutonymphs and mated females. Neurosecretory regions in these developmental stadia are described in relation to their positions adjacent to individual neuropilar ganglia.
Organization of interstitial tissue in the testis of the salamander Necturus maculosus (Caudata: Proteidae)
Authors: Pudney Jeffrey , Callard Gloria V.
Published: February 2005

In Necturus maculosus the organization of the interstitial tissue varies according to the stage of spermatogenesis. Leydig cells at various stages of differentiation and myoid cells are always present in this tissue. The Leydig cells are undifferentiated at all phases of germ cell activity and only hypertrophy following spermiation and degeneration of Sertoli cells. These Leydig cells are structurally analogous to mammalian Leydig cells. They do not form part of the lamina propria of the seminiferous lobules and hence cannot be referred to as lobule‐boundary cells previously described in the urodele testis (Lofts, '74). When the Leydig cells hypertrophy, numerous unmyelinated axons appear in the interstitial tissue. These axons, often devoid of Schwann‐cell cytoplasm, occur in close proximity to Leydig cells. Because the levels of both Substance P and neurotensin increased in the testis of Necturus maculosus as Leydig cells differentiated, we concluded that these neural elements may regulate Leydig‐cell function locally, through the release of neuropeptides.
Cellular and ultrastructural features of the adult and the embryonic eye in the marine gastropod, Ilyanassa obsoleta
Authors: Gibsonm Barbara L.
Published: February 2005

Light and electron microscopic techniques show that the eye of the marine prosobranch gastropod, Ilyanassa obsoleta, is composed of an optic cavity, lens, cornea, retina, and neuropile, and is surrounded by a connective tissue capsule. The adult retina is a columnar epithelium containing three morphologically distinct cell types: photoreceptor, pigmented, and ciliated cells. The retina is continuous anteriorly with a cuboidal corneal epithelium. The neuropile, located immediately behind the retina, is composed of photoreceptor cell axons, accessory neurons, and their neurites. The embryonic eye is formed from surface ectoderm, which sinks inward as a pigmented cellular mass. At this time, the eye primordium already contains presumptive photoreceptor cells, pigmented retinal cells, and corneal cells. Several days later, just before hatching, the embryonic eye remains in intimate contact with the cerebral ganglion. It has no ciliated retinal cells, neuropile, optic nerve, or connective tissue capsule and its photoreceptor cells lack the electron‐lucent vesicles and multivesicular bodies of adult photoreceptor cells. As the eye and the cerebral ganglion grow apart, the optic nerve, neuropile, and connective tissue capsule develop.
Head skeleton of the marine catfish Arius tenuispinis day (Osteichthyes: Siluriformes, Ariidae)
Authors: Rao K. Srinivasa , Lakshmi K.
Published: February 2005

The osteology of the head skeleton of marine catfish Arius tenuispinis is described in detail. The skeletal elements of the different regions are dealt with categorically. Bones of the ethmoidal, orbitotemporal, auditory, and occipital regions of the cranium; and the upper jaw, lower jaw, hyoid arch, hypobranchial, and opercular series of the visceral skeleton are described in detail. Identity of the ectopterygoid, mesopterygoid, and metapterygoid is established in accordance with the current nomenclature and accepted homologies. The shelving bone of the epiotic is found to be large, having articulation with the parapophyses of the complex vertebra. The head skeleton of A. tenuispinis conforms to the normal siluroid pattern.
External and internal sexual dimorphism in leiognathid fishes: Morphological evidence for sex‐specific bioluminescent signaling
Authors: McFall‐Ngai M. J. , Dunlap P. V.
Published: February 2005

Fourteen species of leiognathid fishes (Perciformes, Leiognathidae) from the Philippine Islands, Thailand, Japan, Indonesia, and Palau were examined for accessory secondary sexual dimorphism. Thirteen species exhibit either external dimorphism (a clear patch of skin on the flanks of males, a large clear patch of skin on the opercular margins of males, or a flank stripe in males) or internal dimorphism (large light organs in males) or both. Eight of the 14 species (and possibly as many as 11) exhibit both forms of sexual dimorphism. Two species show only internal light organ volume dimorphism, and one species shows neither external nor internal dimorphism. Sexual dimorphism is thus very common in leiognathids. The externally dimorphic skin patches are closely associated with the internally dimorphic light organ system in seven species (and possibly as many as ten), indicating a potential for light emission through the clear patches. A bioluminescent signaling function by males is therefore suggested for the sexual dimorphism in leiognathids, which may play an important role in the schooling behavior as well as in species and sexual recognition of these coastal fishes.
Fine structure of antennal putative thermo‐/hygrosensilla of adult Rhodnius prolixus Stål (Hemiptera: Reduviidae)
Authors: McIver Susan , Siemicki Roman
Published: February 2005

At least five nonporous sensilla with inflexible sockets (npsensilla) occur on each antenna of both sexes of adult Rhodnius prolixus. Externally the sensillum appears as a short, rounded peg set into a pit surrounded by a depression. A very electron‐dense material occurs in the peg lumen and the inner aspect of the pit. Filamentous extensions of this material radiate into the overlying outlets.

Each sensillum is innervated by three neurons with unbranched dendrites. Two dendrites extend to the peg tip and distally are covered by a dendritic sheath. The portion of these dendrites within the sheath contains a large number of microtubules. The third dendrite terminates near the base of the dentritic sheath and partially wraps around the other two dendrites. Three sheath cells are associated with each sensillum.

Based on similarities in structure with sensilla of known function it is probable that the np‐sensilla of R. prolixus are thermo‐/hygrosensilla responding to cold, dryness and wetness. The sensilla have a number of structural similarities with insect rectal sheath cells known to absorb atmospheric water by electroosmosis. Possibly this process leads to volumetric alterations of cuticular elements associated with the dendrites and ultimately to mechanotransduction.
Anatomy of raccoon (Procyon lotor) and coati (Nasua narica and N. nasua) forearm and leg muscles: Relations between fiber length, moment‐arm length, and joint‐angle excursion
Authors: McClearn Deedra
Published: February 2005

Muscle architecture, moment arms, and locomotor movements in the distal limb segments of the procyonids Nasua (coati) and Procyon (raccoon) are analyzed with reference to patterns of muscle fiber length. This study addresses the hypothesis that relative fiber lengths among muscles in a muscle group can be predicted on the basis of correlates of muscle tension. The results include the following: (1) consistent patterns of fiber length of muscles in a muscle group exist within and between the two genera. (2) Differences in fiber length between muscles can be accounted for by two principal correlates of muscle excursion—length of a muscle's moment arm about a joint and jointangle excursion. (3) Muscle fiber pinnation permits increased tendon excursion, but this effect is relatively small in comparison to the effects of moment‐arm length and joint‐angle excursion. (4) Corollary action between two or more joints (or lack thereof) is an important factor in determination of fiber lengths.
Variation of lymphoid activity in the spleen of a migratory bird, the pied flycatcher (Ficedula hypoleuca; Aves, passeriformes)
Authors: Fänge Ragnar , Silverin Bengt
Published: February 2005

The size and microscopic structure of the spleen of the migratory pied flycatcher (Ficedula hypoleuca) show marked changes during the reproductive cycle. Upon the spring return to their northern breeding sites, the birds have a small spleen with little lymphoid activity and a poorly developed red pulp. During the breeding period the volume of red and white pulp increases, the number and distinctness of lymphoid follicles (germinal centres) in the white pulp increase, and groups of cells with intensely basophilic cytoplasm, probably B cells (plasma cells), appear. The findings suggest that the immune system of the adult pied flycatcher is activated during periods when it is bound to the nest.

Young flycatchers beginning their autumn migration also show a marked increase of lymphoid activity in the spleen.
Maturation and aging of adult fat body and oenocytes in Drosophila as revealed by light microscopic morphometry
Authors: Johnson M. B. , Butterworth F. M.
Published: February 2005

A morphological and cytometric analysis of the adult fat body cells and oenocytes was made on sections of abdomens from immature, mature and senescent Drosophila melanogaster of both sexes. There are about 18,000 fat body cells in abdomens of female and mature male flies. Immature and senescent males have about 12,000 and 15,000 cells, respectively. The size of the cells is almost the same for immature flies of both sexes and increases about six‐fold to approximately 2600μm2, so that mature flies of both sexes have equivalent amounts of fat body tissue. The proportions of lipid, glycogen, and background cytoplasm of fat body cells also remain relatively constant throughout adult life, but dense, proteinaceous granules are observed in cells of senescent flies. The amounts of cellular components change dramatically due to change of cell size with age; the amount of lipid shows the greatest sexual difference with about 2 × more in the females at all stages studied. The oenocytes number about 6,000 in the abdomens of all but immature male flies, which have approximately 4,000. Although the cells of both sexes triple in size to about 700 μm2, the oenocytes of males reach maximum size earlier than those of females. The major features of oenocytes appear to be dense background cytoplasm, putative lipid droplets found only in mature flies, and pigmented granules first seen in the cells of mature flies which accumulate with age to 33% of the cytoplasm. The number of cells and their anticipated capacity for protein synthesis is discussed in relation to the production of yolk protein precursors.
The arterial arches and their interpretation in Bipes and other amphisbaenians
Authors: Renous D'Sabine
Published: February 2005

The study of the arterial arches of Bipes, the only amphisbaenian with forelimbs, resolves the problem of the interpretation of the structure of the arterial arches in other forms of this group of squamate reptiles. In Bipes, as in turtles, the subclavian and common carotid arteries originate from a brachiocephalic trunk, which arises from an innominate trunk deriving from the right aortic loop.

This interpretation is not only original but also emphasizes the important lengthening of the brachiocephalic part relative to the strictly carotidian one. It supposes the intercalation of a new “precardiac” region between the pectoral girdle and the heart; these two components are closely associated topographically in the quadrupedal Squamata. This lengthening, expressed by the increase in the number of precloacal vertebrae, is linked with the increase in the asymmetry of the aortic loop.
Ultrastructural analysis of spermiogenesis in Admetus pomilio (Arachnida, amblypygi)
Authors: Tripepi Sandro , Saita Abele
Published: February 2005

The mature spermatozoon of Admetus pomilio is a spherical cell containing nucleus and tightly coiled flagellum. In early spermatids the Golgi apparatus forms the acrosomal vesicle and at the opposite side the distal centriole gives rise to the axonemal complex of the sperm tail. As the nucleus elongates, chromatin forms twisted filaments and the spermatid nucleus takes on a helical form. Microtubules are juxtaposed with the nucleus envelope, which is separated from a central chromatin mass by an electron lucid region. A long perforatorium, located on the border of the chromatin mass, runs helically in the nucleus from the centriolar region to subacrosomal space. During tail elongation, the anterior part of the axoneme is surrounded by a long, spiral mitochondrial sheath. In the late spermatid, chromatin filaments appear twisted and become aggregated. The nucleus and flagellum undergo further contortions in which the nucleus coils and the flagellum winds up into the body of the cell and coils in a regular fashion. The mitochondrial sheath surrounds about 2/3 of the 9 + 3 axoneme. These features of spermatid ultrastructure resemble those in the primitive Liphistiomorpha.
Morphological and structural study of Landolt's club in the chick retina
Authors: Quesada A. , Génis‐Gálvez J. M.
Published: February 2005

Light and electron microscopy were used to study Landolt's club of the bipolar cells in the newborn chick retina as well as in early embryonic stages. In the embryo, the bipolar cells were connected to the outer limiting membrane by Landolt's club. Some of the bipolar cells disconnect from this membrane, by complete retraction of Landolt's club, giving rise to bipolar cells without this process. The newly hatched chick, was used for analysis of the ultrastructure of Landolt's club. Zones of apposition between Muller cells and Landolt's club are associated with cytoplasmic vesicles in both cells. Muller cells appear to transmit vesicular material, possibly nutrients, to bipolar cells through Landolt's club. Thus, Landolt's club provides substrates to bipolar cells in the poorly vascularized region of the chick retina.
Tadpole erythrocytes: Luminescent properties with dark field microscopy
Authors: Tyler Lisa W. , Piotrowski Deborah C. , Kaltenbach Jane C.
Published: February 2005

To characterize and classify erythrocytes of ranid tadpoles, alcohol‐fixed blood smears were studied with dark field illumination. All preclimax stage (limb bud‐foot) Rana castesbeiana tadpoles from ponds in Massachusetts had red blood cells that were polymorphic. The majority of cells (88%) showed a bright, granular luminescence varying from white to blue‐grey, whereas, cytoplasm of the other cells was smooth, black, and nonluminescent. On the other hand, tadpoles in similar stages from other species (Rana clamitans, Mass. and Rana pipens, Vermont) and from R. catesbeiana tadpoles from other locations (Wisconsin and North Carolina) had no observable cytoplasmic luminescence in any of their red blood cells. Moreover, as Mass. R. catesbeiana underwent metamorphic climax their luminescent cells disappeared and were replaced by small, round, dark, nonluminescent cells, precursors of the oval, nonluminescent erythrocytes characteristic of adult frogs. Cells with black nonluminescent cytoplasm generally contained nuclei which were luminescent. In conclusion, two main types of red blood cells‐those with and those without cytoplasmic luminescence‐are distinguishable with dark field microscopy. Luminescence of the cells varies with species, geographic location, and developmental stage of the tadpoles.
Functional characteristics of the calf muscles of the rat
Authors: Woittiez R. D. , Baan G. C. , Huijing P. A. , Rozendal R. H.
Published: February 2005

Length‐force relations, both active and passive, and twitch contraction characteristics were quantified for the entire complex of the superficial calf muscles, as well as individually for the Mm. soleus, plantaris, and gastrocnemius, caput mediale and laterale, of eight male Wistar rats. The M. soleus composes approximately 5% of the weight and cross‐sectional area of the entire group of superficial calf muscles and is the only muscle of the group containing mainly slow‐twitch fibers. The other superficial muscles of the calf are primarily fast‐twitch muscles.

The mono‐articular M. soleus, the bi‐articular M. gastrocnemius, caput mediale and laterale, and the poly‐articular M. plantaris differ with respect to the number of joints crossed. However, contrary to the findings for cat hind limbs (Goslow et al. [1977] J. Morphol. 153:23–38), the muscles of the complex of superficial calf muscles of the rat did not differ with respect to (a) their fiber optimum length, (b) their maximum length range of active force generation, (c) the relative increase of passive force owing to lengthening of the muscle, (d) the angle of the ankle at which they produce maximal active force (the knee angle was fixed at 90°).
Distribution of myofiber types in thigh muscles of chickens
Authors: Suzuki A. , Tsuchiya T. , Ohwada S. , Tamate H.
Published: February 2005

The composition of myofiber types varies within thigh muscles of chickens. The present study was designed to determine whether or not myofiber types were distributed uniformly across the diameter of the thigh muscles of chickens. Cross sections from middle portions of muscles were used histochemically to examine differences in distribution and composition of myofiber types in the muscles. Myofibers that reacted moderately (M) or strongly (S) for myosin adenosine triphosphatase (ATPase) after preincubation at pH 4.3 were classified as type I. Type I myofibers reacted weakly (W), moderately (M), or strongly (S) for ATPase after preincubation at pH 10.6; these type I myofibers were subclassified into four types (ISW, ISM, ISS, and IMM). Myofibers that reacted negatively for acid‐stable ATPase and strongly for alkali‐stable ATPase were classified into two types: type IIA, with strong NADH tetrazolium reductase (NADH‐TR), and type IIB, with weak NADH‐TR activity. The M. pubo‐ischio‐femoralis pars lateralis had numerous type IIA myofibers and very few type ISM myofibers, whereas the pars medialis had many type IMM myofibers and few type ISS and IIA myofibers. The type I group of myofibers did not exceed about 50% in the other muscles, which had one to three types of type ISW, ISM, and ISS myofibers. The Mm. femorotibiales had more type ISW, and ISM myofibers in the deep regions near the femur than in the superficial regions. The M. iliotibialis cranialis, M. iliofibularis, and M. flexor cruris medialis had more type ISW, ISM, or ISS myofibers in the medial regions than in the lateral regions. A few type ISW myofibers were scattered in the cranial part of M. iliotibialis and in the M. ambiens. The M. flexor cruris lateralis pars pelvica had type IIA and IIB myofibers exclusively. All the muscles had type IIA myofibers. Type IIB myofibers existed in the muscles except the M. puboischio‐femoralis. Type IIA and IIB myofibers differed in proportion in different muscles and in their different regions. The type I group of myofibers was generally concentrated more in the deep regions near the femur and in the medial regions than in the superficial and lateral regions of the thigh muscles. The distribution of type IIA myofibers resembled that of type I group. Type IIB myofibers showed a distribution opposite to that of type I group and IIA myofibers. The spatial distribution of myofiber types within individual muscles can account for the various locomotory and postural requirements of the thigh.
Ontogeny of hemopoietic and lymphopoietic tissues in the lizard Chalcides ocellatus (Reptilia, Sauna, Scincidae)
Authors: El Deeb Somaya , Zada Suher , El Ridi Rashika
Published: February 2005

The first and major blood‐forming organ to develop in the viviparous lizard Chalcides ocellatus is the yolk sac, which exhibits prominent erythropoietic activity from as early as stage 21 through birth (stage 41). Myeloid cells and megakaryocytes are produced in the yolk sac from stage 23 onward. During lizard embryogenesis hemopoietic activity is also observed in spleen and bone marrow but in neither kidney nor liver. Cells capable of giving rise to lymphocytes both in vivo and in vitro are first found in the thymus at stage 35. Active lymphopolesis in thymus and spleen begins at stages 36 and 39, respectively. In contrast, the gut‐associated lymphoid aggregates are not evident before birth.
Electron microscopy of the medial cortex in the lizard Psammodromus algirus
Authors: Davila J. C. , Guirado S. , De La Calle A. , Marin‐Giron F.
Published: February 2005

The medial cortex of Psammodromus presents a three‐layer organization. Most of the cell bodies are localized in a compact lamina, the cellular layer. Two plexiform layers, superficial and deep, enclose the cellular layer. The most external portion of the superficial plexiform layer is formed by a limiting glial sheet consisting of tanycytic processes that reach the surface of the cortex. Astrocytes are localized close to the glial sheet. There are two types of axon terminals within the superficial plexiform layer: type S with spheric vesicles and type F with pleomorphic vesicles. Large solitary neurons are present at middle levels of the layer. In the cellular layer there are three neuronal types: large neurons with dispersed chromatin, neurons of medium size with chromatin clumps, and electron‐dense neurons. Protoplasmic astrocytes are found superficially in this layer. In the deep plexiform layer numerous neuronal cell bodies are visible, and three types can be distinguished: horizontal fusiform cells, globous neurons with indented nuclei, and electron‐dense neurons. Protoplasmic astrocytes are present throughout this layer. Oligodendrocytes are more frequent in the inner third of the layer, often related to fibers of a thick fascicle running in contact with the ependyma, the alveus. The ependyma is formed by a single row of prismatic cells bordering the lateral ventricle.
Microcirculation in mouse spleen (nonsinusal) studied by means of corrosion casts
Authors: Schmidt E. E. , MacDonald I. C. , Groom A. C.
Published: February 2005

Corrosion casts of mouse spleen, examined by scanning electron microscopy, enabled vascular pathways of the arterial, intermediate, and venous circulations to be traced over considerable distances. The arterial tree is surrounded by white pulp immediately upon entering at the hilus, and relatively few arterioles extend into red pulp. A profusion of capillaries is present in both periarterial lymphatic sheaths and lymphatic nodules, arranged as bifurcating systems (rather than anastomosing networks) terminating in the marginal sinus (MS) and marginal zone (MZ). The MS, which is situated between white pulp and MZ, consists of a discontinuous layer of flattened anastomosing spaces which are up to six times as large as those in rat spleen. Extensive filling of the entire MZ took place before appreciable filling of surrounding red pulp occurred. Capillary terminations in red pulp are always continuous with reticular meshwork, i.e., no evidence for a “closed” circulation was found. Casts of the venous origins support the classification “pulp venules” rather than “venous sinuses” and show major morphological differences from the richly anastomosing system of sinuses in rat. In the subcapsular region of mouse spleen large anastomosing veins ramify over the surface, with reticular meshwork occupying extensive areas between adjacent veins. For in vivo microscopy this arrangement offers advantages over that found in rat spleen (accompanying paper), where almost the entire surface is densely covered with venous sinuses.
Anatomy of membranous mouthpart cuticles and their roles in feeding in black flies (Diptera: Simuliidae)
Authors: Sutcliffe James F.
Published: February 2005

The nature and extent of the cuticular membranes of the mouthparts of females of Simuiium venustum are described. These membranes are arranged into four groups: (1) cuticular membranes of the labium/hypopharynx; (2) membranes of the apical labrum; (3) those of basal portions of the mandibles and laciniae; and (4) the labral flaps within the syntrophial food canal.

From their external and internal structure it is concluded that membranes of the first three groups go through inflation/deflation cycles directly related to the food‐pumping rhythm. It is further concluded that these membranes line the inner and outer syntrophial and proboscis surfaces, acting as pressure seals both to prevent blood loss from the wound and air entry into the food canal during feeding. The labral flaps within the food canal appear to act as one‐way valves, keeping blood from leaking out between the mouthparts during the pumping downstroke but allowing pooled blood to enter during the upstroke.
The heart of the dugong (Dugong dugon) and the west indian manatee (Trichechus manatus) (Sirenia)
Authors: Rowlatt U. , Marsh H.
Published: February 2005

Thirty‐eight dugong (Dugong dugon) hearts and 28 Florida manatee (Trichechus manatus) hearts were obtained from stranding programs in Australia and the United States. In addition to a double ventricular apex, a feature that has astonished scientists since the eighteenth century, the hearts of both animals have a double subvalvular conus and a dorsal left atrium. The heart lies in a vertical plane at right angles to that of the completely dorsal, symmetrical lungs. The dugong heart has a deeper interventricular cleft and a more conical left ventricle. The latter features may be part of a general morphological trend toward specialization for a more energetic aquatic existence. The presence of a bulbous ascending aorta in the manatee but not in the dugong is without explanation.
Morphology, ultrastructure, and germ cell cluster formation in ovarioles of aphids
Authors: Büning Jürgen
Published: February 2005

The structure of aphid ovaries, including ovipare and virginopare morphs of five species, was investigated by light and electron microscopy. Aphids contain telotrophic meroistic ovarioles. The amount and distribution of cytoplasmic components of nurse cells, nutritive cords, and young oocytes are nearly identical to those known from scale insects and heteropterans. Each ovariole has a constant number of nurse cells and oocytes. In ovaries of ovipare morphs, the nurse cell nuclei enlarge by endomitosis (n = 28n−210n), whereas in virginopare morphs the nurse cell nuclei remain small (n = 22n−24n). Furthermore, in virginoparae the previtellogenic growth of oocytes is highly reduced, and vitellogenesis and chorionogenesis are blocked totally. Embryogenesis starts immediately after the shortened previtellogenic growth.

In each ovariole, all germ cell descendants belong to one germ cell cluster that follows the 2n rule. The cluster normally contains 25 = (32) cells, but other mostly smaller numbers also occur. In contrast to polytrophic meroistic ovarioles, more than one cell of each cluster will develop into an oocyte. In Drepanosiphum platanoides, 16 (2n−1) nurse cells and 16 (2n−1) oocytes exist in each cluster, whereas, in Metopolophium dirhodum, 8 (2n−2) oocytes and 24 (2n−1 + 2n−2) nurse cells are normally found. In many ovarioles of Macrosiphum rosae, 21 nurse cells nourish 11 oocytes. Models of germ cell cluster formation in aphid ovaries are discussed.