bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of the kidney of adult bowfin, Amia calva, with emphasis on “renal chloride cells” in the tubule
Authors: Youson John H. , Butler David G. 
Published: February 2005

AbstractThe nephron of adult bowfin, Amia calva, was described using light and electron microscopic techniques. The kidney of the bowfin possesses an abundant supply of renal corpuscles with each consisting of a glomerulus and a Bowman's capsule of visceral (podocyte) and parietal layers. No juxtaglomerular apparatus is present. The epithelium of the tubule is continuous with the parietal epithelium and is divisible in descending order into neck, first proximal, second proximal, first distal, second distal, and collecting segments. The tubules drain into a complex system of collecting ducts that ultimately unite with the main excretory duct, the archinephric duct. Mucous cells are the dominant cell throughout the entire ductular system. Nephrostomes are dispersed along the kidney capsule.The neck segment has a ciliated epithelium, and while both proximal segments possess a prominent brush border, the fine structure of the first implies involvement in protein absorption and the second in the transport and reabsorption of solutes. The cells of the first distal segment are characterized by deep infolding of the plasma membrane and a rich supply of mitochrondria suggesting the presence of a mechanism for ion transport. The second distal segment is composed of cells resembling the chloride cells of fishes and these cells are present in progressively decreasing numbers in the collecting segment and duct system so that only a few are present in the epithelium of the archinephric duct. The “renal chloride cells” possess an abundant network of smooth tubules and numerous mitochondria with a rich supply of cristae. Glycogen is also a conspicuous component of these cells. The presence of “renal chloride cells” in this freshwater holostean, in other relatively primitive freshwater teleosts, and in larval and adult lampreys is discussed with reference to both phylogeny and the need for a special mechanism for renal ion conservation through absorption.
Cellular organization and peritrophic membrane formation in the cardia (Proventriculus) of Drosophila melanogaster
Authors: King David G. 
Published: February 2005

AbstractThe peritrophic membrane of Drosophila melanogaster consists of four layers, each associated with a specific region of the folded epithelial lining of the cardia. The epithelium is adapted to produce this multilaminar peritrophic membrane by bringing together several regions of foregut and midgut, each characterized by a distinctively differentiated cell type. The very thin, electron‐dense inner layer of the peritrophic membrane originates adjacent to the cuticular surface of the stomadeal valve and so appears to require some contribution by the underlying foregut cells. These foregut cells are characterized by dense concentrations of glycogen, extensive arrays of smooth endoplasmic reticulum, and pleated apical plasma membranes. The second and thickest layer of the peritrophic membrane coalesces from amorphous, periodic acid‐Schiff‐positive material between the microvilli of midgut cells in the neck of the valve. The third layer of the peritrophic membrane is composed of fine electron‐dense granules associated with the tall midgut cells of the outer cardia wall. These columnar cells are characterized by cytoplasm filled with extensive rough endoplasmic reticulum and numerous Golgi bodies and by an apical projection filled with secretory vesicles and covered by microvilli. The fourth, outer layer of the peritrophic membrane originates over the brush border of the cuboidal midgut cells, which connect the cardia with the ventriculus.
Studies on the subcommissural organ of Salmo gairdneri
Authors: Schäfer Heike , Blüm Volker 
Published: February 2005

AbstractThe light microscopic analysis of serial sections of the subcommissural organ (SCO) of the rainbow trout (Salmo gairdneri) shows that the form of the groove‐like (in cross section) organ varies over its total length. Its rostral origin is a tunnel‐like structure anterior to the orifice of the hollow pineal stalk. The SCO forms the dorsal wall of the brain. Caudally the SCO is increasingly displaced from the surface of the brain by the fibers of the posterior commissure; the organ ends in a tabular area beyond the latter. The orifice of the pineal stalk is surrounded by the ependyma of the SCO that invaginates like a funnel and joins with the ependyma of the pineal stalk after a considerable narrowing. The rudimentary parapineal organ is located on the left side of the brain and is connected with the left habenular ganglion through the parapineal tract. It contacts the third ventricle with a short channel within the ependyma of the SCO. The histological organization of the ependymal and hypendymal cells of the SCO is typical of teleosts. Secretory material is located basally and apically in relation to the nucleus, but there is no indication of a basal secretory release. Basal ependymal processes terminate with broadened endings at the membrana limitans externa. The apical product is discharged into the third ventricle, where it aggregates into the thread‐like structure of Reissner's fibre. The SCO cells have no direct contact with cerebral or meningeal blood vessels.
Morphology of defense glands of the opilionids (daddy longlegs) Leiobunum vittatum and L. flavum (Arachnida: Opiliones: Palpatores: Phalangiidae)
Authors: Clawson Robert C. 
Published: February 2005

AbstractOpilionid defense glands consist of 0.5 × 0.9‐mm sacs attached to the underside of low tubercles located on the dorsal side of the cephalothorax, posterior to the first pair of legs. Each gland opens via an elongated slit, located in the posterior floor of a crater that is situated at the summit of the tubercle. The center of the sac, called the reservoir, is lined by a cuticle consisting of epicuticle and endocuticle which is continuous through the slit with the exoskeleton. The layers of cuticle vary in thickness with different locations in the gland. A hemocoelomic (basement) membrane, 0.5–1, μ thick, forms the boundary between glandular cells and hemocoel. The gland has a nonsecretory portion consisting only of cuticle‐supporting cells and a secretory portion consisting of secretory and cuticle‐supporting cells. The cuticle lining the reservoir in the secretory area is broached by many cuticle‐lined ductules, each of which drains an isolated intercellular space called the intercalated cistern. This in turn drains microvilli‐lined canaliculi located between and extending into secretory cells. The cisterns are devoid of microvilli. Secretory cell cytoplasm contains a Golgi apparatus, many free ribosomes, rough endoplasmic reticulum (RER), two types of granules (speckled and dense), and mitochondria. Speckled granules are partially filled with fairly large particles and are found in association with the Golgi apparatus. They also surround canaliculi into which they empty. Dense granules are packed with very small particles, have a gray homogeneous appearance, and are scattered throughout the cytoplasm. Mitochondria containing matrix granules tend to scatter throughout the cytoplasm but are concentrated around canaliculi.
Aspects of shell formation in eggs of the tuatara, Sphenodon punctatus
Authors: Packard Mary J. , Thompson Michael B. , Goldie Kenneth N. , Vos Marta 
Published: February 2005

AbstractThe flexible shell from eggs of the tuatara (Sphenodon punctatus) is comprised of both calcareous and fibrous components. The calcareous material is organized into columns that extend deep into the fibrous shell membrane. Many of the fibers of the membrane are enclosed within the crystalline matrix of the columns. Columns widen and flatten slightly at the outer surface of the eggshell to form cap‐like structures composed of a compact crystalline matrix containing no fibers. The outer surface of eggs laid prior to completion of shell formation consists of a series of nodes obscured by a densely fibrous matrix. Similar nodes also are found at the inner surface of partially shelled eggs. The nodes represent the outer and inner aspects of columns that had not completed formation prior to oviposition. Our interpretation is that a layer (or layers) of the shell membrane forms first, with nucleation of columns occurring shortly thereafter. Columns grow into the membrane a short distance and enclose fibers of the membrane, but the primary direction of column growth is toward what will become the outer aspect of the shell. Calcareous columns and the shell membrane form more or less in concert until crystal growth outstrips that of the membrane and a cap‐like apex of compact crystalline material is formed. The end result is an eggshell in which the shell membrane and calcareous material form a single unit for much of the thickness of the shell.
Some histological aspects of the hip joint capsule in the vervet monkey
Authors: Walji A. H. 
Published: February 2005

AbstractMicroscopic studies show that the capsule of the hip joint in the vervet monkey (Cercopithecus aethiops pygerythrus) is preponderantly collagenous. Among the collagen fiber bundles are varying quantities of elastic fibers that demonstrate a definite, differential regional distribution. The highest concentration of elastic tissue is found in the posterior, postero‐inferior, and inferior aspects of the hip joint capsule, whereas the anterior and superior aspects of the capsule are preponderantly collagenous. It is postulated that this regional distribution of elastic tissue is related to the differential functional requirements of the posterior, postero‐inferior, and inferior aspects of the capsule for flexibility and stretchability. These requirements appear to be a consequence of the habitual postures and locomotory positions assumed at the hip joint by these primarily quadrupedal primates. Collagen, on the other hand, being much more resistant to deformation and relatively noncompliant, is the predominant tissue in the anterior and superior aspects of the joint.
On the nervous system of Velella (hydrozoa: Chondrophora)
Authors: Mackie G. O. , Singla C. L. , Arkett S. A. 
Published: February 2005

AbstractSilver impregnations, immunofluorescence microscopy, and electron microscopy of the nervous system of Velella confirm previous reports that there are two nerve nets, one composed of small and the other of “giant” neurites. Only one of these systems, the small‐fibered open one, shows FMRFamide‐like immunoreactivity. It appears to be primarily a sensory network. Despite presence of a neuropeptide in these neurons, they did not contain dense‐cored vesicles. The “giant” nerve net (closed system) shows many connections that appear syncytial in the silver preparations. While it is confirmed that gap junctions are present between some neurites in the closed system, it is likely that fusion of neurites also occurs and that the system is a partial syncytium. Membrane complexes with gap junctions are abundant in the cytoplasm. It is suggested that fusion occurs by the engulfment of small neurons by large, resulting in an excess of cell membrane, which is internalized with gap junctions still intact. These internalized membranes appear to break up into vesicles eventually. A similar process may occur in the “giant” swimming motor neuron net of the medusa Polyorchis.
Adrenergic innervation of the large arteries and veins of the semiarboreal rat snake Elaphe obsoleta
Authors: Donald John A. , Lillywhite Harvey B. 
Published: February 2005

AbstractFluorescence histochemsitry was used to study the adrenergic innervation of the large arteries and veins at six points along the body of the semiarboreal rat snake Elaphe obsoleta. Apart from the vessels adjacent to the heart, there was a marked contrast in the density of adrenergic innervation of anterior and posterior systemic arteries and veins. The anterior arteries and veins have little adrenergic innervation in contrast to the extremely dense innervation of the arteries and veins posterior to the heart. The innervation pattern is consistent with known physiological adjustments to gravity and suggests a mechanism for regulating dependent blood flow via sympathetic nerves. In comparison to the posterior systemic arteries, parallel segments of pulmonary artery taken from the same body position of Elaphe contained a much sparser innervation by adrenergic nerves. The sparser innervation can be correlated with less gravitational disturbance in the pulmonary artery, which is relatively short in this and in other arboreal snakes.
Afferent projections of the trigeminal nerve in the goldfish, Carassius auratus
Authors: Puzdrowski R. L. 
Published: February 2005

AbstractThe horseradish peroxidase (HRP) histochemical technique was used to examine the peripheral distribution and afferent projections of the trigeminal nerve in the goldfish, Carassius auratus. Sensory fibers of the trigeminal nerve distribute over the head via four branches. The ophthalmic branch distributes fibers to the region above the eye and naris. The maxillary and mandibular branches innervate the regions of the upper and lower lip, respectively. A fourth branch of the trigeminal nerve was demonstrated to be present in the hyomandibular trunk.Upon entering the medulla the trigeminal afferent fibers divide into a rostromedially directed bundle and a caudally directed bundle. The rostromedially directed bundle terminates in the sensory trigeminal nucleus (STN) located within the rostral medulla. The majority of fibers turn caudally, forming the descending trigeminal tract. Fibers of the descending trigeminal tract terminate within three medullary nuclei: the nucleus of the descending trigeminal tract (NDTV), the spinal trigeminal nucleus (Spv), and the medial funicular nucleus (MFn). All projections, except for those to the MFn, are ipsilateral. Contralateral projections were observed at the level of the MFn following the labeling of the ophthalmic and maxillomandibular branches. All branches of the trigeminal nerve project to all four of the trigeminal medullary nuclei. Projections to the STN and MFn were found to be topographically organized such that the afferents of the ophthalmic branch project onto the ventral portion of these nuclei, while the afferents of the maxillo‐ and hyomandibular branches project to the dorsal portion of these nuclei.Cells of the mesencephalic trigeminal nucleus were retrogradely labeled following HRP application to the ophthalmic, maxillary, and mandibular branches of the trigeminal nerve. In addition to demonstrating the ascending mesencephalic trigeminal root fibers, HRP application to the above‐mentioned branches also revealed descending mesencephalic trigeminal fibers. The descending mesencephalic trigeminal fibers course caudally medial to the branchiomeric motor column and terminate in the ventromedial portion of the MFn.
Role of actin filaments in shape formation of mesenteric mesothelial cells of the bullfrog
Authors: Sugimoto Keiji , Fujii Sachiko , Ichikawa Yasuaki , Nakamura Itsuo 
Published: February 2005

AbstractThe role of actin filaments in the development of cellular shape in the mesenteric mesothelium of the bullfrog was studied by using a simple, new technique for making en face preparations of mesothelial sheets. By using these mesothelial cell preparations, the distribution of actin was determined by means of fluorescence microscopy with 7‐nitrobenz‐2‐oxa‐1,3‐diazole (NBD)‐phallacidin and that of myosin by means of immunofluorescence microscopy. Although fluorescence produced by both NBD‐phallacidin and antimyosin staining was found exclusively along the margins of the cells, its intensity was altered in correspondence with changes in cell shape. For instance, tadpole‐type mesothelial cells with either and irregular or very slender cell shape showed very weak fluorescence. On the other hand, frog‐type mesothelial cells with a polygonal shape showed intense fluorescence at their margins and had circumferential bundles of acting filaments at their apices. Furthermore, intercellular junctions between the mesothelial cells developed as the cell shape became polygonal during metamorphosis. The present study showed that development of circumferential bundles of acting filaments and intercellular junctions may serve to establish and maintain the definitive polygonal cellular pattern in the mesenteric mesothelium of the bullfrog.
Morphology of congenital microphthalmia in chicks (Gallus gallus)
Authors: Ehrlich David , Stuchbery John , Zappia Joe 
Published: February 2005

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

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

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

AbstractThe chelonian carapace is composed of the endochondral ribs and vertebrae associated with a specialized dermis. The ribs are found in an aberrant position compared to those of all other tetrapods; they are superficial and dorsal to the limb girdles. This morphological arrangement, which constitutes the unique chelonian Bauplan, is examined from a developmental perspective. Embryos of Chelydra serpentina were studied during stages of carapace development. Tissue morphology, autoradiography, and indirect immunofluorescent localization of adhesion molecules indicate that the outgrowth of the embryonic carapace occurs as the result of an epithelial–mesenchymal interaction in the body wall. A carapacial ridge composed of mesenchyme of the dermis and overlying ectoderm is formed dorsal to the ectodermal boundary between somitic and lateral plate mesoderm. It is the anlage of the carapace margin, in which the ribs will eventually terminate. The ectoderm of the carapacial ridge is thickened into a pseudostratified columnar epithelium, which overlies a condensation in the mesenchyme of the dermis. Patterns of cell proliferation and the distribution of N‐CAM and fibronectin in the carapacial ridge are consistent with patterns seen in other structures initiated by epithelial–mesenchymal interactions such as feathers and limb buds.Based on an analogy to this developmental mechanism in the development of the limb skeleton, a further analogy with the evolution of the limbs from lateral fin folds is used to form a hypothesis on the evolution of the carapace from elements of the primitive reptilian integument.
Sperm storage within the oviduct of turtles
Authors: Gist Daniel H. , Jones Jeffery M. 
Published: February 2005

AbstractTubules containing sperm were identified by light microscopy in the oviducts from 11 species of turtles representing six different families. Sperm storage tubules were found in a small region of the posterior portion of the egg albumin‐secreting section of the oviduct located between the infundibulum and the uterus. This location of storage tubules, midway between the ovary and vagina, is unique among vertebrates. Ducts, restricted to the posterior albumin region, connect the tubules to the oviduct lumen, allow entrance of sperm to the tubules. Sperm were identified in tubules of female turtles isolated from males for as long as 423 days.