bluuebunny/crossref_metadata_2025 huggingface dataset:
Perivascular lymphoid tissue associated with the axillary lymph sinus and the lateral vein of Gehyra variegata (Reptilia: Gekkonidae)
Authors: Johnston M. R. L.
Published: February 2005

The axillary sinus of G. variegata is formed from a perivascular lymphatic which locally invests the lateral vein. Within the sinus the wall of the vein is distended by lymphoid tissue which is itself supported by reticular fibres. Lymphocytes, reticular cells, macrophages and mast cells occur in the tissue. The overall appearance of the structure is lymph node‐like. Although Cardianema sp. (Nematoda:Filarioidea) parasitised the lymphatic system of some geckos examined, the non‐pathologic origin of the lymphoid tissue is indicated by its presence in both axillae of infected and uninfected geckos alike. Comparison is made with lymph nodes and node‐like structures in other vertebrates.
Fine structure of the abdominal neural fat‐body sheath in the stick insect (Carausius morosus, Br.)
Authors: Huddart H. , Greenwood M. , Oates K.
Published: February 2005

The neural fat‐body sheath surrounding the abdominal ventral nerve cord of Carausius morosus has been examined by light and electron microscopy. A perineural chamber between the ventral nerve cord and the sheath is present in the ganglionic regions, but in the interconnective regions the sheath directly covers the neural lamella. The sheath is differentiated into secretory cells with abundant granular endoplasmic reticulum and many mitochondria and storage cells with lipid droplets and granules presumed to be glycogen. The whole sheath is pervaded with tracheoblast cells and associated tracheal and tracheolar tubules. Recent evidence suggests that this sheath may have little power of ionic regulation. The function of the sheath, deduced from the fine structure described here, appears to be to serve the nutritional needs of the central nervous system. Why a sheath of this type appears to be confined to herbivorous insects with unusual haemolymph cationic balance is still unexplained.
Differentiation of the myoepithelial cells of the rat submandibular gland in vivo and in vitro: An ultrastructural study
Authors: Cutler Leslie S. , Chaudhry Anand P.
Published: February 2005

Cytodifferentiation of the myoepithelial cells (MEC) of the rat submandibular gland (SMG) was observed by studying the prenatal and postnatal development of the gland in vivo and in vitro by light and electron microscopy. The anlage of the SMG first appeared on the fourteenth day of gestation and, from its earliest inception, was surrounded by an intact basal lamina. Presumptive myoepithelial cells were first seen at 18 days of gestation coinciding with the onset of secretion in the rudiment. These cells were flattened, peripherally located and subjacent to the epithelial basal lamina. Initial deposition of cytofilaments in the MEC's was observed during the first three days following birth and fully matured cells were seen as early as one week after birth. Presumptive and immature MEC's were observed undergoing mitosis, but once cytofilament deposition had begun in the cells they did not divide. Myoepithelium developed in relation to embryonic secretory structures and were only observed surounding acini and intercalated ducts in the adult gland. New myoepithelial cells were formed as long as new acinar‐intercalated duct units were formed. Myoepithelial cells did not produce secretory type granules at any time during their development or in their mature state.

Development of the MEC's in vitro paralleled that in vivo and supported the above observations.
Ultrastructure of the larval compound setae of the polychaete Nereis vexillosa grube
Authors: Gustus Rita M. , Cloney Richard A.
Published: February 2005

Larval compound (jointed) setae of the polychaete Nereis vexillosa Grube were examined by scanning and transmission electron microscopy and by polarization microscopy. Long‐bladed spinigers and short‐bladed falcigers are described. The proximal shaft of each of these types of setae flares distally into a serrated collar and encloses the proximal end of a toothed blade. The collar projects on one side as a boss. The blade and the cortex of the shaft have longitudinal channels. A large excentric cavity in the shaft (the medullary channel) contains a loose meshwork of trabeculae. In the distal part of the shaft these trabeculae are aggregated into diaphragms. The seta is invested with an electron dense layer of enamel. Juvenile setae contain both chitin and protein. With respect to the long axis of the seta, the blade and the cortex of the shaft are positively birefringent and the medullary diaphragms are negatively birefringent. KOH extraction renders the setae negative to a test for protein and reverses the sign of birefringence of the cortical material of the shaft.
Effects of growth hormone and nutrient on limb regeneration in hypophysectomized adult newts
Authors: Sato Norimitsu L. , Inoue Sakae
Published: February 2005

The effect of hypophysectomy, growth hormone (GH) and an amino acid‐glucose mixture on the regenerative ability of the hypophysectomized Triturus pyrrhogaster yielded the following results:

The survival time of hypophysectomized newts can be prolonged substantially by the sulfamide application.

Although the limb regeneration in the hypophysectomized newt is retarded as compared with that of the pituitary intact control, it finally completes morphogenetic process under such conditions of prolonged survival.

The injection of 100 μg of GH restored the speed of regeneration of pituitary‐deprived limbs to almost a normal level.

Injections of the amino acid‐glucose mixture also promoted the limb regeneration in hypophysectomized newts. However, initial delay in regeneration to the time of bud appearance was not restored by the nutrients.
Histology of the neurosecretory system and neurohaemal organs of the spider, Argiope aurantia (Lucas)
Authors: Babu K. Sasira
Published: February 2005

Histological studies of the neurosecretory system during the postembryonic development of a spider, Argiope aurantia, were made at the light‐microscopic level.

Neurosecretory cells which are found in all stages are classified into type I and type II cells. The type I cells are present in the aboral region of the brain and in pedipalpal, ambulatory and abdominal ganglia of the subesophageal mass. The type II cells which appear from the seventh stage are confined to the cheliceral ganglia. Three stages of secretory activity (poor, medium and full) based on stainability are described in these cells.

In both types clear axonal transportation of neurosecretory material is observed. The discrete tracts and commissures formed by these neurosecretory axons are described in the brain and subesophageal ganglion. The complexity of some of these pathways is comparable to that of the ordinary neurons.

One pair of nerves from the brain and four pairs of nerves from the subesophageal mass enter a neurohaemal organ, the Tropfenkomplex. This is a paired structure, situated dorsally, on either side of the subesophageal mass. The neurosecretory axons branch extensively within the organ and on their course they from sacs or pools filled with secretory material.

The Tropfenkomplex is enveloped by a thin neural sheath which runs deep into the organ dividing it into a series of lobes. Glial cells are distributed within the organ. As in the neurosecretory cells, changes in stainability of secretory material were also observed in the Tropfenkomplex.

During intermolt periods two peaks of stainability have been noticed. The first peak lasts for 24 hours after the molt, and this is followed by a low activity period between second and fifth day. From the sixth to the tenth day after the molt the second peak commences. It is suggested that the second peak may be responsible for bringing about molting.

The cheliceral group appears (seventh stage) at a time when external indication of reproductive characters are visible. In the ninth stage, by the tenth day after the last molt, several of the type I and type II cells contain much secretion. This is followed by maturation of gonads and oviposition. Thus both type I and type II cells are believed to be involved in the reproduction of the animal.
Observations on the gametolytic gland in the anaspidean opisthobranchs, Phyllaplysia taylori and Aplysia californica
Authors: Brandriff Brigitte , Beeman Robert
Published: February 2005

The wall of the gametolytic gland in Aplysia and Phyllaplysia consists of a muscular layer lined with an epithelium incorporating four distinct cell types, some of which show intense secretory activity. The cytoplasm of these cells, rich in RNA, has a peripheral layer of densely‐packed mitochondria in association with a smooth endoplasmic reticulum. Lipid globules, perhaps resulting from absorption of lumen contents by microvilli, appear in the cytoplasm in the course of growth and reproductive activity. A basal band of fibrillar material appears to serve as a cytoplasmic skeleton. The elaboration of cell types, extensive areas of cytoplasmic RNA, and vigorous secretory activity suggest important roles for this organ such as development of food reserves, recycling of sexual materials of high physiological value, and interaction with the bag cells of the nervous system in coordinating ovulation with the availability of capacitated, exogenous sperm.
Sheath configurations in human cuspal enamel
Authors: Weber Dennis F.
Published: February 2005

To determine the prism sheath configurations in human cuspal enamel 80 teeth were initially ground to produce flat surfaces through the following planes: a horizontal series at successively greater distances from the dentinoenamel junction and longitudinally through the center of the cusps. Individual teeth were suspended in an acid‐alcohol solution (1 cm3 conc. HCl in 100 cm3 95% ethanol) at 37°C for seven to ten days. The treatment “softened” the enamel to a depth of approximately 1 mm. The teeth were embedded in Epon and sectioned at 0.5 to 10 μm with a diamond knife. Thick and thin ground sections for phase contrast microscopy and acid‐etched ground sections for Nomarski differential interference microscopy were prepared through the same regions. In thicker longitudinal sections, the prisms in gnarled enamel formed a zig‐zag pattern which was unlike the twisting pattern generally observed in ground sections. The thinnest transverse sections showed the sheath outlines to be dramatically different from those seen elsewhere in the enamel. Some prism sheaths were circular, others were in the form of spirals. What could be described as sheaths within sheaths were also seen. In the thinnest longitudinal sections the prisms were seen to be elongated and discontinuous. Sheath outlines in enamel adjacent to the central core of gnarled enamel were similar to those described elsewhere in the body of the enamel. Keyhole, modified keyhole patterns and arcade forms were the dominant sheath patterns. Other atypical sheath configurations were seen scattered throughout this region.
Retinal projections in the northern water snake Natrix sipedon sipedon (L.)
Authors: Northcutt R. Glenn , Butler Ann B.
Published: February 2005

Retinal projections were studied experimentally in the Northern water snake using modifications of the Nauta silver impregnation technique. Contralaterally, the retina projects to nucleus geniculatus lateralis pars dorsalis and pars ventralis, nucleus lentiformis mesencephali and nucleus geniculatus pretectalis. A sparse projection was also observed to nucleus ovalis. An additional afferent thalamic projection to nucleus ventrolateralis was found in two cases. The retina projects ipsilaterally to the dorsolateral portion of nucleus geniculatus lateralis pars dorsalis, and sparsely to nucleus lentiformis mesencephali and nucleus geniculatus pretectalis. Nucleus posterodorsalis receives dense bilateral retinal projections. Contralaterally, the retina also projects to the superficial layers of the tectum (layers 8–13 of Ramón) and to nucleus opticus tegmenti. Armstrong's findings that the retinal projections in Natrix are qualittatively similar to those in lizards were confirmed. However there are marked quantitative differences among the various pathways and their corresponding nuclei. These differences are particularly striking in comparing the visual projections to the dorsal thalamus, the retino‐tecto‐rotundal and the retino‐geniculate systems. The first is reduced in volume and the second is markedly increased in volume in comparison with lizards. These data lend support to the theories of Walls that snakes evolved from fossorial lizards and of Underwood that the eyes of these lizards underwent reduction but not complete degeneration. Qualitatively the retinal projections are conservative among lizards and snakes, but a history of reduction of these pathways in ancestral snakes with a selective increase in the retino‐geniculate system as a surface niche was reattained is reflected in the anatomy of this ophidian visual system.
Fine structure of the torus semicircularis of some teleosts
Authors: Ito Hironobu
Published: February 2005

Fine structure of the torus semicircularis of the loach, carp, common eel and rainbow trout was studied by light and elecron microscopy. The torus semicircularis of each species is divided into four layers. The subependymal first layer comprises numerous unmyelinated fibers and their terminals which contain cored vesicles. The second and the third layers are composed of small cell bodies and their dendrites respectively. These layers develop equally in the four species and contain the usual axodendritic synapses. On the other hand, the fourth layer varies in different species. The mediumsized cells in this layer, which are inferred to be of the same origin as the small cells from their configuration and size, show differences in lamination in each species. Compared with the usual axodendritic synapse of the small cells, the medium‐sized cells have quite different synaptic patterns, which include inhibitory and electrical as well as the usual excitatory chemical synapses. From these findings, the medium‐sized cells are surmized to receive sound of different degrees of intensity from that received by the small cells, which may have an effect on feeding behaviors of the species. In the deepest portion of the torus semicircularis of all species, there are large multipolar cells on which numerous axon terminals synapse in much the same way as they do on the medium‐sized cells. These findings suggest that the synaptic patterns in the torus semicircularis may depend not on the receptive cells in each layer but on the various characteristics of the afferent fibers.
An ultrastructural analysis of the cuticle, epidermis and esophageal epithelium of Eisenia foetida (Oligochaeta)
Authors: Burke Janice M.
Published: February 2005

The epidermis of Eisenia is covered by a cuticle and rests on a basement lamella. The cuticle, which is resistant to a variety of enzymes, is composed of non‐striated, bundles of probable collagen fibers that are orthogonally oriented and are embedded in a proteoglycan matrix. The basement lamella consists of striated collagen fibers with a 560 Å major periodicity. Proximity and morphology suggest that the epidermis may contribute to both the cuticle and the basement lamella — that is, the single tissue may synthesize at least two types of collagen. The epidermis is a pseudostratified epithelium containing three major cell types (columnar, basal and gland) and a rare fourth type with apical cilia. The esophagus is lined by a simple cuticulated epithelium composed predominantly of a single cell type, which resembles the epidermal columnar cell. Rare gland cells occur in the esophageal epithelium, but basal cells are lacking.
The lizard ear: Gekkonidae
Authors: Wever Ernest Glen
Published: February 2005

The gecko ear was studied in 36 species belonging to 24 genera. This receptor has attained an advanced level of structure and performance in this group of lizards, but there are many variations among species. To a large extent these variations follow subfamily lines as represented in Kluge's system of classification.

Brief consideration is given to features of the outer and middle ear, but chief concern is with inner ear structures and their relations to auditory sensitivity as represented by the cochlear potentials.

The auditory papilla is segmented, with a dorsal portion whose hair cells have their ciliary tufts attached to a tectorial membrane, and a ventral portion in which these cells form tow assemblages, one with tectorial connections and the other with connections to a line of sallets.

The dorsal segment varies greatly in length and in the form of ciliary orientation. In Eublepharinae and most Gekkoninae the ciliary orientation is unidirectional, and the degree of sensitivity relates to the length of this segment. In Diplodactylinae and Sphaerodactylinae the orientation is bidirectional, and this segment functionally hardly differs from the ventral segment.

Auditory sensitivity as measured in terms of the cochlear potentials shows close relations with subfamily groupings, except for the Gekkoninae in which considerable diversity is found.

The evidence from structural differentiation, along with that derived from the forms of the cochlear potential functions, leads to the suggestion that these ears possess a high degree of pitch discrimination and capability for the analysis of complex sounds.
Fine structure of the dorsal ocellus of the worker honeybee
Authors: Toh Yoshihiro , Kuwabara Masutaro
Published: February 2005

The three dorsal ocelli of worker honeybees have been studied by light and electron microscopy. Each ocellus has a single flattened spheroidal lens and about 800 elongated retinular cells. Retinular cells are paired and form a two‐part plate‐like rhabdom between their distal processes. Each rhabdomere comprises parallel microvilli projecting laterally from the apposed retinular cells. Primary receptor cell axons synapse within the ocellus with ocellar nerve fibers of two different calibers. Each ocellus has eight thick fibers ca 10 m̈m in diameter and several thinner ones less than 3 m̈m in diameter. Fine structural evidence suggests that retinular axons end presynaptically on both types of ocellar nerve fibers. Since all retinular cells apparently synapse repeatedly with the thick fibers this involves a convergence of about 100:1. Thick fibers always terminate postsynaptically within the ocellus while thin fibers terminate presynaptically on other thin fibers, thick fibers or retinular axons. Structural evidence for synaptic polarization indicates that retinular cells and thick fibers are afferent, thin fibers efferent. Thus complex processing of the ocellar visual input can occur before the secondary neurons of the three ocelli converge to form the single short ocellar nerve which runs to the posterior forebrain.
The functional anatomy of the forelimb of some african viverridae (Carnivora)
Authors: Taylor M. E.
Published: February 2005

The functional morphology of the forelimbs of the following African Viverridae was studied, Atilax paludinosus, Bdeogale crassicauda, Civettictis civetta, Genetta genetta, G. tigrina, Helogale parvula, Herpestes ichneumon, H. sanguineus, Ichneumia albicauda, Mungos mungo, Nandinia binotata. Their locomotory behaviour has been previously studied and described and is related to morphological differences. The osteology of all the species and the myology of three species is described. The species have been assigned to primary locomotor categories on the basis of their locomotion. These are 1, climbing, arboreal walking; 2, arboreal and terrestrial walking and jumping; 3, general terrestrial walking and scrambling; and 4, trotting. In the climbing arboreal walking category the most distinctive morphological adaptations are powerful flexors and extensors as well as a flexible plantigrade manus with retractile claws. In the arboreal and terrestrial walking category the shoulder, elbow and carpal joints are flexible and the manus has retractile claws, though the flexor and extensor musculature is insufficiently developed for controlled climbing. The trotting category is characterised by a high humero‐radial index and a rigid antibrachium. The foot is digitigrade with the claws short and stout. Species in the general walking and scrambling category show many differences in the morphology of their feet, even though the proximal parts of the forelimb appear similar. Due to the restricted nature of the adaptations, these species have been assigned to secondary locomotor categories. Morphological characters typical of the locomotor categories are summarized in the discussion.
Histology and histochemistry of developing outgrowths of Corvomeyenia carolinensis harrison (Porifera: Spongillidae)
Authors: Harrison Frederick W.
Published: February 2005

Laboratory‐reared outgrowths of the freshwater sponge Corvomeyenia carolinensis Harrison were examined using histological and histochemical techniques, supplemented by phase contrast observations of cellular behavior. The tissue and cellular components of the spongillid outgrowth region were defined in terms of function and morphogenic state. Archeocytes differ considderably, in both histochemical and morphological characteristics, from other cell types of the adult sponge, being histochemically similar to stem cells reported from a variety of developmental series. Archeocytes exhibit cytological characteristics of unspecialized cells capable of high levels of synthetic activity while other cell types of C. carolinensis, for the most part, can be characterized as fully differentiated cells displaying more restricted synthetic capabilities but often accumulating neutral mucoproteins. The presence of aggregates of amebocytes, not identifiable as archeocytes and possibly engaged in gemmule formation, is discussed in terms of current concepts of gemmulation and cellular developmental capabilities in sponges.
An electron microscopic study of the circulatory system in Nereis japonica
Authors: Nakao Taisuke
Published: February 2005

Blood vessels in Nereis japonica were studied by electron microscopy. It was found that blood vessels regardless of location were similar in the basic organization of the basal lamina and the usual presence of collagen fibrils on the vessel wall. Differences arise, depending on whether the outside of the basal lamina is covered by peritoneal cells, by gut epithelium, or by epidermis. These relate to the location of the vessels in mesenteries, gut or epidermis, but do not reflect basic structural differences in the vessels themselves. Furthermore, it was concluded that true endothelial cells do not exist in the circulatory system of Nereis japonica and that, in this respect, the system is essentially different from that of vertebrates, in which endothelial cells line the vessels of a closed circulatory system. These considerations lead to the further conclusion that the vascular lumen in Nereis is essentially interstitial space and that the system, which has been known as a typical “closed” circulatory system in annelids, is actually an open circulatory system. Peritoneal cells covering the walls of internal vessels show various degrees of muscular differentiation and those possessing myofilaments may be called “myomesothelial cells.”
The mammalian testicular capsule and its muscle elements
Authors: Leeson Thomas S. , Cookson Frank B.
Published: February 2005

This study of the testicular capsule of rat, dog, cat and human has confirmed the presence of three layers, viz., the tunica vaginalis, the tunica albuginea proper and an innermost tunica vasculosa. Smooth muscle cells are present in the tunica albuginea of all four species and are more prominent at the posterior pole of the testis where the capsule merges with the mediastinum testis. In the rat and the dog, a few striated muscle fibers also are present.

While the tunica albuginea is to be considered as a dense connective tissue, the arrangement of the collagen bundles and the presence of a relatively high content of elastic fibers probably permits changes in size of the testis following spontaneous contractions of the muscle elements, which are known to occur. The role of the testicular capsule in sperm transport is discussed in relation to other factors, the spontaneous contractions of the capsule presumably having a “pumping” action and aiding the movement of non‐motile spermatozoa from the testis to the epididymis.

The presence of striated muscle fibers in two species is of interest and, while these may function in a similar manner to the smooth muscle, they may represent simply an unusual differentiation of embryonic myoblasts.
Postembryonic eye degeneration in the troglobitic salamander Typhlotriton spelaeus
Authors: Besharse Joseph C. , Brandon Ronald A.
Published: February 2005

Comparative histological observations of the eyes of Typhlotriton spelaeus and several epigean, plethodontid species indicate that the principal postembryonic degenerative changes in the eyes of T. spelaeus involve the eyelids and cornea, visual cells, outer plexiform layer, and the pigment epithelium. Ordinarily these changes were initiated after metamorphosis, before attainment of sexual maturity, but a few larvae had degenerating retinae.

The corneal epithelium becomes irregular and thin as eyelids develop during and after metamorphosis, but retains its larval structure in animals in which eyelid overlap is incomplete. Disruption and vacuolation of the lens sometimes occurs in postmetamorphic animals with degenerating visual cells. Retinal degeneration involves reduction of the inner and outer segments of visual cells, loss of the outer plexiform layer, and retraction of apical processes of the pigment epithelium. In its earliest stage, retinal reduction is first apparent at the retinal margin where visual cells are normally less well‐differentiated, but in its terminal stage reduction has gone to completion over the entire retina. Extent of retinal degeneration in adults is directly related to postmetamorphic age but there is variability in each age group. Females generally have smaller eyes, and more extensive degeneration of visual cells than males. The loss of visual function in adults is correlated with extensive visual cell degeneration.
Correlation of light and electron microscopic hemocyte structue in the dictyoptera
Authors: Ratcliffe N. A. , Price C. D.
Published: February 2005

As part of program of research into insect cellular immunity, an integrated light and electron microscopic study of the hemocytes of seven members of the Order Dictyoptera has been made. In fresh hemolymph, five cell types, the prohemocytes, plasmatocytes, granular cells, spherule cells and cystocytes, are easilv distinguished. However, in thick Araldite sections and in thin sections in the electron microscope it is sometimes difficult to identify the various cell types. The reasons for this difficulty are discussed.

Granules with a microtubular substrcture are found in the plasmatocytes, spherule cells and cystocytes. In the plasmatocytes these granules have a different ultrastructure than those in the spherule cells and cystocytes. The in vitro fragility of these granules in both the spherule cells and cystocytes during coagulation partially explains the previous confusion in distinguishing these two cell types.

Evidence is presented which indicates that the plasmatocytes, granular cells and spherule cells represent a developmental series originating from the prohemocytes. Where exactly the cystocytes are derived from is unknown.
Ultrastructural studies of regenerating spines of the sea urchin Strongylocentrotus purpuratus I. Cell types without spherules
Authors: Heatfield Barry M. , Travis Dorothy F.
Published: February 2005

The fine structure of regenerating tips of spines of the sea urchin Strongylocentrotus purpuratus was investigated. Each conical tip consisted of an inner dermis, which deposits and contains the calcite skeleton, and an external layer of epidermis. Although cell types termed spherulecytes containing large, intracellular membrane bound spherules were also present in spine tissues, only epidermal and dermal cell types lacking such spherules are described in this paper.

The epidermis was composed largely of free cells representing several functional types. Over the apical portion of the tip these cells occurred in groups, while proximally they were distributed within longitudinal grooves present along the periphery of the spine from the base to the tip. The terminal portions of apical processes extending from some of the epidermal cells formed a thin, contiguous outer layer consisting of small individual islands of cytoplasm bearing microvilli. Adjacent islands were connected around the periphery by a junctional complex extending roughly 200 Å in depth in which the opposing plasma membranes were separated by a narrow gap about 145 Å in width bridged by amorphous material. Other epidermal cells were closely associated with the basal lamina, which was 900 Å in thickness and delineated the dermoepidermal junction; some of these cells appeared to synthesize the lamina, while others may be sensory nerve cells.

The dermis at the spine tip also consisted of several functional types of free cells; the most interesting of these was the calcoblast, which deposits the skeleton. Calcoblasts extended a thin, cytoplasmic skeletal sheath which surrounded the tips and adjacent proximal portions of each of the longitudinally oriented microspines comprising the regenerating skeleton, and distally, formed a conical extracellular channel ahead of the mineralizing tip. The intimate relationship between calcoblasts and the growing mineral surface strongly suggests that these cells directly control both the kinetics of mineral deposition and morphogenesis of the skeleton. Other cell types in the dermis were precalcoblasts and phagocytes. Precalcoblasts may function as fibroblasts and are possible precursors of calcoblasts. Closely associated with the basal lamina at the dermoepidermal junction were extracellular unbanded anchoring fibrils 150 Å to 200 Å in diameter. Scattered proximally among dermal cells were other extracellular fibrils, presumably collagenous, about 300 Å in diameter with a banding periodicity of 210 Å.
Presomal morphology and development of Prosthorhynchus formosus, Prosthenorchis elegans, and Moniliformis dubius (Acanthocephala)
Authors: Wanson Warren W. , Nickol Brent B.
Published: February 2005

Larvae removed at one‐day intervals from laboratory infected intermediate hosts provided material for a comparative study of presomal development in Prosthorhynchus formosus (Van Cleave, '18) Travassos, '26, Prosthenorchis elegans (Diesing, 1851) Travassos, '15, and Moniliformis dubius Meyer, '33. Acanthellae begin development soon after entering intermediate hosts' hemocoels, and by the 18th day all three species possess three nuclear masses representing primordia of the proboscis, proboscis receptacle and ganglion, and trunk musculature and genitalia.

Presomal development of P. formosus and P. elegans results in structures concurring with morphology of other adult palaeacanthocephalans and archiacanthocephalans. Development of M. dubius, however, differs from that of other archiacanthocephalans in that the muscular receptacle wall lines the entire surface of the nonmuscular sheath, failing to form a ventral cleft characteristic of other archiacanthocephalans. Unlike receptacle protrusor muscles of other archiacanthocephalan species, those of M. dubius spiral around the receptacle as they extend posteriad to attach individually to a pouchlike, muscular thickening at the receptacle's base. These protrusor muscles are distinct from the receptacle wall, as attested by their development alongside neck retractor muscles, not from the receptacle primordium, and the manner in which they are left to trail behind the receptacle when it is drawn anteriorly into the proboscis during larval development. The proboscis receptacle of M. dubius should not be thought of as being double‐walled, as envisioned by previous workers.
Olfactory bulb projections in the bullfrog Rana catesbeiana
Authors: Northcutt R. Glenn , James Royce G.
Published: February 2005

The projections of the accessory and main olfactory bulbs of the bullfrog are described as part of a long term analysis of the morphological differences in amphibian and reptilian telencephalons. Unilateral aspiration of the accessory olfactory bulb results in an ipsilateral projection to the pars lateralis of the amygdala via the accessory olfactory tract. Degenerating fibers from the accessory olfactory bulb are tracable into the cell‐free zone between the dorsal striatum and the lateral pallium, and projections to these neural populations may also exist. Unilateral lesions of the main olfactory bulb reveal two major secondary pathways: an ipsilateral medial olfactory tract that projects to the rostral ventromedial portion of the medial pallium, the postolfactory eminence and the rostral, lateral and medial septal nuclei; and an ipsilateral lateral olfactory tract that projects to the dorsal striatum, the lateral pallium and the ventral half of the dorsal pallium. Two crossed secondary olfactory pathways to the contralateral telencephalon decussate via the habenular commissure after entering the ipsilateral stria medullaris. A crossed lateral pathway terminates in the dorsal striatum, the caudal, lateral pallium and the ventral portion of the dorsal pallium. A crossed medial pathway terminates in the internal granule layer of the main olfactory bulb.
The interstitial origin of germinal cells in the testis of the stickleback
Authors: Ruby Sylvia M. , McMillan Donald B.
Published: February 2005

The brook stickleback,Culaea inconstans(Kirtland), in common with other bony fishes, lacks a germinal epithelium in the tubules of the testis, and the tubule wall is composed of a thin, discontinuous layer of myoid cells and collagenous fibers. Labelling of germ cells with tritiated thymidine has shown that the germ cells are derived from clumps of spermatogonia in the interstitial area. Large companion cells within the lumina of the tubules extend their processes to engulf spermatogonia from the interstitium which then enter the lumen of the tubule. Subsequent development of the germ cells takes place within individual compartments formed by folds of the plasma membrane of a companion cell. The companion cell, together with its complement of germ cells, constitutes a cyst. A companion cell may surround spermatogonia in the interstitium and at the same time encompass residual sperm of the previous season within the lumen. The plasma membranes of the germ cells and the companion cells remain discrete. Mature sperm are released into the lumen of the tubule and the companion cell again extends its processes into the interstitium and engulfs more spermatogonia for the following year.

Companion cells may be homologous to the Sertoli cells of higher vertebrates although their processes penetrate the interstitium during the initial stages of spermatogenesis and they do not contain a permanent stock of spermatogonia.
The long‐term organ culture of tissues from adult Necturus maculosus, the mud puppy
Authors: Brown Dennis , Fleming Norman , Monnickendam Marjorie A. , Balls Michael
Published: February 2005

Fragments of Necturus maculosus liver, spleen and kidney were cultured at 25°C in 50% Minimal Essential Medium (MEM) or 50% Leibovitz L‐15 Medium (L‐15) for up to 49 days. The integrity of tissue structure was evaluated, hepatocyte cell and nuclear volumes were measured, the respiration rates of freshly‐isolated and cultured liver fragments were determined, and the mitotic incidences in cultured liver, spleen and kidney were estimated. The addition of adrenalin caused a reduction in the glycogen content of liver cultures, and the subsequent addition of insulin resulted in a net increase in glycogen synthesis. Glycogen levels fell in fragments cultured in L‐15, but rose in cultures in MEM. Arginase and ornithine transcarbamylase levels fell gradually throughout a 49‐day culture period in L‐15. Evidence presented supports the position that the survival of tissues in vitro is related to cell size and respiration rate. These experiments show that N. maculosus is a suitable donor of tissues for long‐term organ culture studies on the maintenance and control of tissue‐type specific structure and function.
A comparative study of the chemical defensive system of tenebrionid beetles III. Morphology of the glands
Authors: Tschinkel Walter R.
Published: February 2005

The morphology of the abdominal defensive glands and associated structures of 115 species of tenebrionid beetles was studied on KOH cleared material. The glands and reservoirs of all Tenebrionidae are homologous and evolved as a pair of sacs from the intersegmental membrane between sternites VII and VIII. On the basis of reservoir morphology and secretory cell tubule termination, seven provisional gland types were established. Several of the types include species from several tribes, and several tribes contain several gland types, indicating possible incongruencies between the taxonomy and phylogeny of the family. Morphological trends in the evolution of the glands include: increase of reservoir capacity, constriction of the proximal portion of the sacs into distinct exit ducts, release of secretion by exuding or spraying rather than everting, and concentration of the secretory cell tubule terminations into restricted fields, collecting ducts or ampullae. The morphology of the glands of 58 species is illustrated and the results are discussed in light of the current taxonomy of the Tenebrionidae.
Ultrastructure of the posterior half of the intestine of the channel catfish, Ictalurus punctatus
Authors: Krementz Anne B. , Chapman George B.
Published: February 2005

The posterior half of the channel catfish intestine has a similar histological organization to that of other teleost fishes. This region is organized into a muscosa, a submucosa, a double layered muscularis and a serosa. A “stratum compactum” of dense connective tissue was confirmed for the submucosa. In its histology and cytology, the midgut resembles the hindgut, except that in the hindgut the muscularis is thicker, the microvilli are shorter, there are fewer absorptive inclusions in the columnar cells and there are more goblet cells. With the exception of the serosa, the tissue layers of the intestine of the 6 cm juvenile catfish are fully developed. The most notable difference between the intestines of the juvenile and adult catfish occurs in the columnar epithelial cells. The mucosal cells of the juvenile catfish contain an abundance of large clear vacuoles while the mucosal cells of the mature catfish contain smaller dense granules. With few exceptions, the ultrastructural details of the cells in the catfish intestine are identical to those of the same cell types of the mammalian intestine.
Evidence for diaphragms in the pores of annulate lamellae and the nuclear membrane
Authors: Ward Robert T. , Ward Elizabeth
Published: February 2005

Interpretation of cross and tangential sections of the annulate lamellae and nuclear membrane of Rana pipiens oocytes provides evidence in these structures for the existence of diaphragms spanning the pores. The evidence appears to rule out explanations ascribing such diaphragms to an optical artifact. More detailed description is given of a component of the pore complex only briefly described heretofore and now called the “intracisternal ring.” The varied results and interpretations of studies of the pore complex in various cells are discussed.
Relationship of the sarcoplasmic reticulum to fibril and triadic junction development in skeletal muscle fibers of fetal monkeys and humans
Authors: Walker Sheppard M. , Schrodt G. Randolph , Currier Glenna J. , Turner E. Victoria
Published: February 2005

Examinations of stages of fibril development in muscle fibers of seven Rhesus monkey and six human fetuses reveal SR tubules encircling the Z lines at all stages of fibril development. The encircling SR tubules are continuous with the SR network of tubules which is found surrounding fibrils at all stages of development observed. The SR tubules encircling the Z lines show connections (electron‐opaque strands) with the Z lines. The developing triadic junction shows a progressive increase in complexity of structures within the junction. First, membranes of T and SR become apposed with no visible structure between them. Second, tenuous connections are found traversing the space between apposed membranes. Third, well developed bridges are seen traversing the space. And finally, an intermediate density midway between the apposed membranes and parallel to them is found in favorable sections. Junctions between T tubule membranes were also observed and the structures in these junctions are somewhat similar to those found in junctions between T and SR membranes. The change in orientation of triads from predominantly longitudinal to predominantly transverse is complete in the 18‐week monkey fetus and incomplete in the latest stage (28‐week) of fetal development observed in humans.
Aspects of germinal cyst and sperm development in Poecilia latipinna (Teleostei: Poeciliidae)
Authors: Grier H. J.
Published: February 2005

The structure of the testis of Poecilia latipinna is described with particular reference to Sertoli cell‐germ cell relationships during development and maturation of the germinal cyst. The cyst develops when primary spermatocytes become surrounded by a single layer of Sertoli cells at the testis periphery. As spermatogenesis and then spermiogenesis proceed, the cyst moves centrally in the testis toward the ducts comprising the vasa efferentia. In addition to being a structural part of the germinal cyst, the Sertoli cells phagocytize residual bodies cast off by developing spermatids and form an association with mature sperm, which resembles that observed in mammals, before the sperm are released into the vasa efferentia as a spermatozeugmata.

The results of this investigation are discussed in view of what is known concerning testis structure in other teleosts and similarities between cell functions in teleosts and mammals. It is concluded that teleost Sertoli cells, teleost lobule boundary cells and mammalian Sertoli cells are homologous.
The feeding system of terrestrial tiger salamanders (Ambystoma tigrinum melanostictum baird)
Authors: Larsen John H. , Guthrie Dan J.
Published: February 2005

High speed cinematography was used to record the feeding activities of terrestrial Ambystoma tigrinum melanostictum. A description of these activities based on films of more than 50 feeding sequences is presented, and the mechanical units involved are defined, described, and functionally analyzed. Evolutionary implications of the feeding system are discussed.

In a typical feeding sequence, A. t. melanostictum stations and maintains its lower jaw 3‐5 mm from the prey. The mouth is then opened to form a gape of ∼60° by raising the anterior end of the flexed skull and by elevating and advancing the trunk while the mental symphysis of the lower jaw remains stationary. As the mouth opens the bulging tongue is recontoured so that the posterior glandular region becomes the tip of the fully protruded tongue, which may extend 3 to 7 mm beyond the symphysis. Dorsally the protruded tongue has a deep central depression and pronounced anterolateral rims. The anterior rim collapses on contact, thereby engulfing the prey in a sticky trough that retains it during tongue withdrawal. The cervical region is then flexed and the skull snaps downward. If the prey resists the tongue and is captured by marginal teeth, A. t. melanostictum relies on repeated tongue protraction and retraction, in some cases accompanied by inertial feeding. Swallowing involves gular expansion and contraction, and is accompanied by eye depression. When the mouth is opened during ingestive activities, the lower jaw remains in place.

Apparently, A. t. melanostictum uses the dorsal trunk, the cucullaris major and the robust heads of the depressor mandibulae muscles to open the mouth. During skull elevation the lower jaw is partially immobilized by the geniohyoideus, and rectus cervicis superficialis muscles. The subarcualis rectus I muscles are prime movers in tongue projection. Hebosteoypsiloideus muscles assist in tongue protrusion by slackening the rectus cervicis profundus muscles that would otherwise restrict anterior displacement of the otoglossal cartilage and copula. Tongue contouring is performed by the complex genioglossus musculature. Sublingual and anterolingual sinuses facilitate protrusion and contouring by providing space and lubrication. Rectus cervicis muscles (profundus and superficialis) are responsible for tongue withdrawal. Closure of the mouth is accomplished by the four levator mandibulae muscles, and again the lower jaw is immobilized, mostly by ventral longitudinal muscles.

Skull‐trunk elevation during prey capture and ingestion was also observed and filmed in several other species of Ambystoma, in Dicamptodon ensatus, and in two salamandrid species. Apparently raising and straightening the craniovertebral axis, while the mental symphysis retains contact with the substratum, is a common feature of urodele feeding systems, and does not require peculiar morphological adaptations.
A reconsideration of the phylogeny of the tetrapod heart
Authors: Holmes E. Bruce
Published: February 2005

After dissecting a variety of vertebrate hearts and extensively reviewing the literature, I have drawn some conclusions concerning the phylogeny of the tetrapod heart that differ from commonly expressed viewpoints in the literature. It is probable that the absence of an interventricular septum in amphibians is a primitive feature (rather than representing a loss). The complete interventricular septum of crocodilians and birds probably evolved primarily from the major horizontal septum of the typical (noncrocodilian) reptilian heart, with a smaller part representing a new development. The interventricular septum of mammals probably also evolved primarily from the reptilian horizontal septum. There is no reason to assume that the mammalian heart and aortic arches evolved directly from a pre‐reptilian stage, as is often assumed. The evidence upon which these conclusions are based is given.
A simplified placenta‐like system for the transport of extraembryonic nutrients during embryogenesis of Bugula neritina (bryozoa)
Authors: Woollacott Robert M. , Zimmer Russel L.
Published: February 2005

Embryos of the marine cheilo‐ctenostome bryozoan Bugula neritina undergo a marked increase in volume (about 500‐fold) during embryogenesis while being retained in a brood chamber. Previous morphological studies indicate that shortly after transfer of the zygote to the brood chamber, the epithelium of the maternally‐derived portion of the brood chamber, the ooecial vesicle, differentiates in regions adjacent to the embryonary space from a squamous to a columnar form suggesting that the parent is involved as a source of extraembryonic nutrients required for the extensive growth of the embryo.

Results of the present ultrastructural study indicate that hypertrophy of the epithelial cells occurs only in that region of the ooecial vesicle which opposes the embryo, that differentiation (and subsequent regression) of the lining are predictable events correlated with the onset (and termination) of embryonic growth, and that hypertrophied cells are well equipped for the synthesis and transport of macromolecular materials across the vesicle wall to the developing embryo. Further, that portion of the embryo's ectoderm (the presumptive metasomal sac) in contact with this hypertrophied epithelium is morphologically specialized for the uptake of nutrients. Finally, shortly before release of the larva, this intimate association of the metasomal sac tissue and the hypertrophied ooecial vesicle lining epithelium is terminated by invagination of the sac and atrophy of the lining.