bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postnatal development of the vomeronasal epithelium in the rat: An ultrastructural study
Authors: Garrosa Manuel , Coca Santiago 
Published: February 2005

AbstractThree basic types of cells are distinguished in the rat vomeronasal epithelium at birth: bipolar neurons, supporting cells, and basal cells. Neurons at this time include both immature and differentiated cells. By the end of the first postnatal week, all neurons show morphological signs of maturity in their cytoplasm, including abundant granular and smooth endoplasmic reticulum, neurotubules, dense lamellar bodies, apical centrioles, and tufts of microvilli. During the third week microvilli are more frequently encountered and appear to be longer and more branched. Supporting cells appear well‐developed by the second day after birth. During the first ten days of life, supporting cells lose their centrioles and all of the complex associated with ciliary generation in the apical zone. Basal cells appear to be more numerous in newborns than in older animals. Protrusions projecting into the lumen are frequently observed in the epithelium of newborn animals, both on the dendrites of neurons and on supporting cells. After the third week, such protrusions are only observed in the transitional zone between the sensory and the non‐sensory epithelia of the vomeronasal tubes. In this transitional zone, a fourth cell type showing apical protrusions with microvilli differentiates. Cytoplasm in this type resembles that of neighboring ciliated cells but has no cilia or centrioles. These transitional cells are considered to be cells in an intermediate state of differentiation, between that of the differentiated neurons and supporting cells of the sensory epithelium and that of the predominate ciliated cells of the non‐sensory epithelium. The results suggest that by the end of the third week the vomeronasal epithelium is morphologically mature.
Three‐dimensional reconstruction and cross‐sectional anatomy of the thigh musculature of the developing chick embryo (Gallus gallus)
Authors: Drushel Richard F. , Caplan Arnold I. 
Published: February 2005

AbstractThe technique of graphical reconstruction by orthogonal projection of serial sections is used to generate three‐dimensional models of embryonic chick thigh musculature at Hamburger‐Hamilton ('51) stages 36 (day 10) and 39 (day 13). Unique and conserved anatomical landmarks are described, which can be used to specify position along the proximo‐distal axis of the thigh from cross‐sectional appearance. These landmarks provide an important reference for both current and future experimentation in which a precise developmental site must be systematically and repeatedly sampled.
Light, electron microscopical, and immunocytochemical investigation of the stomach wall of the tigerfish Hydrocynus forskahlii
Authors: Coetzee Heleen L. , Nel Maria M. , Swanepoel J. H. , Van Aswegen G. 
Published: February 2005

AbstractThe wall of the stomach of the tigerfish is described and compared with that of other vertebrates. Light microscopic and ultrastructural characteristics of the stomach wall correspond to a large extent to those of other vertebrates, although some differences are found. The mucosa contains (1) surface epithelium characterized by narrow columnar cells with abundant mucous granules; (2) gastric glands consisting of pepsinogenic cells of variable height, containing tubulovesicles and bearing microvilli; (3) five granulated cell types located basally in the epithelium (types 1–5); and (4) lamina propria and muscularis mucosae. Connective tissue separating smooth muscle fibers of the muscularis mucosae constitutes a stratum compactum. The submucosa contains a loose connective tissue, a tunica muscularis of inner circular and outer longitudinal layers, and a serosa of mesothelium and subjacent connective tissue. Immunocytochemical tests with antisera to five polypeptides show gastrin/cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP) immunoreactivities in some cells of the gastric glands, and somatostatin in cells lying among epithelial cells lining the gastric luminal surface or gastric pits.
Unusual membranous network with spines in the uterus of Xiphinema coomansi (Nematoda: Longidoridae)
Authors: de Kruger Johan C. W. , Heyns Juan 
Published: February 2005

AbstractAn ultrastructural study of the uterus of Xiphinema coomansi reveal that the numerous uterine spines present in this species are not anchored to the inner wall of the tubular uterus, but are symmetrically arranged and attached in a membranous network suspended throughout the entire length of the uterus. The spines are solid, hexagonal structures enveloped and connected in tri‐radial fashion to each other, as well as to the inner uterine wall by a continuous thin undulating membrane. The network membrane thus formed encloses numerous compartments on the luminal side of the uterus, which seems to create a type of barrier between the plicated uterine wall and a rather constricted central lumen. No such membranous intrauterine network has been reported previously in the reproductive system of nematodes.
Implications of bone morphology for moa taxonomy and behavior
Authors: Kooyman Brian 
Published: February 2005

AbstractThe limb bone skeleton of the moa, a family of extinct ratite birds endemic to New Zealand, is described with particular reference to the anatomical and functional significance of osteological landmark form variation. The results generally support the existing classification of moa. Four genera, Megalapteryx, Anomalopteryx, Dinornis, and Pachyornis, were found to be evolved within moa, with Emeus and Euryapteryx possibly being more primitive. Megalapteryx was found to be less mobile than other moa genera. The Dinornis species were found to be more cursorial and more mobile relative to other moa. They may also have had a different center of gravity. A marked development of the lower leg in Anomalopteryx suggested a digging habit associated with food procurement.
Ultrastructure of prostomial photoreceptors in four marine polychaete species (annelida)
Authors: Rhode Birgit 
Published: February 2005

AbstractThe photoreceptors of four polychaete species were investigated by transmission electron microscopy: Eteone longa and Anaitides mucosa (Phyllodocidae), Scolelepis squamata (Spionidae), and Heteromastus filiformis (Capitellidae). Four different types of light‐sensitive organs could be distinguished: 1) a simple, unpigmented rhabdomeric type; 2) a simple ocellus composed of a sensory and a pigmented cell; 3) complex eyes with a lens consisting of secretory granules; 4) a simple, unpigmented type with modified cilia. In spite of its simpler organization the fourth type is listed last, because its function as a photoreceptor seems dubious.The first type (unpigmented rhabdomeric receptor) occurs in all four species investigated. It is the only type of photoreceptor in Heteromastus. Additionally, the two phyllodocids Eteone and Anaitides possess another kind of receptor (type 4) in close proximity to the type 1 receptor. Simple ocelli (type 2) are found in Scolelepis. A pair of complex eyes (type 3) is present in both Eteone and Anaitides, but they show important differences in the two species. First, the eyes in Eteone exhibit ciliary rudiments within the sensory processes, but such rudiments are absent in the eyes of Anaitides. Secondly, the sensory cells in Anaitides possess pigment granules, whereas in Eteone they do not. Thirdly, the lens in Eteone is composed of secretion granules of equal electron density, whereas in Anaitides the lens granules show increased electron density centrally. Lens material appears to be secreted from a single corneal cell in Eteone, and from several corneal cells in Anaitides. In both species these corneal cells are located distally outside the lens.
The follicular placenta of the viviparous fish, Heterandria formosa. I. Ultrastructure and development of the embryonic absorptive surface
Authors: Grove Bryon D. , Wourms John P. 
Published: February 2005

AbstractEmbryos of the poeciliid Heterandria formosa develop to term in the ovarian follicle in which they establish a placental association with the follicle wall (follicular placenta) and undergo a 3,900% increase in embryonic dry weight. This study does not confirm the belief that the embryonic component of the follicular placenta is formed only by the surfaces of the pericardial and yolk sacs; early in development the entire embryonic surface functions in absorption. The pericardial sac expands to form a hood‐like structure that covers the head of the embryo and together with the yolk sac is extensively vascularized by a portal plexus derived from the vitelline circulation. The hood‐like pericardial sac is considered to be a pericardial amnion‐serosa. Scanning and transmission electron microscopy reveal that during the early and middle phases of development (Tavolga's stages 10–18 for Xiphophorus maculatus) the entire embryo is covered by a bilaminar epithelium whose apical surface is characterized by numerous, elongate microvilli and coated pits and vesicles. Electron‐lucent vesicles in the apical cytoplasm appear to be endosomes while a heterogeneous group of dense‐staining vesicles display many features characteristic of lysosomes. As in the larvae of other teleosts, cells resembling chloride cells are also present in the surface epithelium. Endothelial cells of the portal plexus lie directly beneath the surface epithelium of the pericardial and yolk sacs and possess numerous transcytotic vesicles. The microvillous surface epithelium becomes restricted to the pericardial and yolk sacs late in development when elsewhere on the embryo the non‐absorptive epidermis differentiates. We postulate that before the definitive epidermis differentiates, the entire embryonic surface constitutes the embryonic component of the follicular placenta. The absorptive surface epithelium appears to be the principle embryonic adaptation for maternal‐embryonic nutrient uptake in H. formosa, suggesting that a change in the normal differentiation of the surface epithelium was of primary importance to the acquisition of matrotrophy in this species. In other species of viviparous poeciliid fishes in which there is little or no transfer of maternal nutrients, the embryonic surface epithelium is of the non‐absorptive type.
Magnetic resonance imaging study of the structure of the yolk in the developing avian egg
Authors: Falen Steven W. , Szeverenyi Nikolaus M. , Packard David S. , Ruocco Martin J. 
Published: February 2005

AbstractMagnetic resonance imaging (MRI) techniques were used to study the morphology of the latebra and concentric rings seen in the yolk of White Leghorn eggs during development of the avian embryo. Previous studies of the macroscopic structure of avian yolk have revealed the latebra, a vaseshaped structure beneath the blastoderm composed of white yolk. The bulbous portion in the center of the yolk is termed the body of the latebra. The thinner portion extending toward the blastoderm is referred to as the neck of the latebra. As the neck of the latebra approaches the blastoderm, it flares out to become the nucleus of Pander. The remainder of the yolk often features alternating concentric layers of white and yellow yolk. These layers, which appear as rings in sections, are thought to represent the daily accumulation of yolk during oogenesis. In this study eggs were imaged with a single slice spin echo sequence using MRI parameters that maximized the visualization of the latebra and concentric rings in the egg yolk. Some experiments were conducted for 2 to 3 day periods with eggs kept in the bore of the magnet using a small incubator that was constructed using a temperature‐controlled water pump. The concentric rings of the yolk and the body of the latebra flatten and become more elliptical during development. The neck of the latebra becomes shorter and disappears around the 7th day of incubation. The body of the latebra starts to become incorporated into the embryo at about the 7th day of incubation and usually disappears by the 13th day. The concentric rings are no longer visible as distinct entities at this time. Histochemical procedures carried out as a result of MRI findings indicate that the latebra is an iron‐rich structure.
An electromyographic analysis of the biting mechanism of the lemon shark, Negaprion Brevirostris: Functional and evolutionary implications
Authors: Motta Philip J. , Hueter Robert E. , Tricas Timothy C. 
Published: February 2005

AbstractThe kinetics of the head and function of select jaw muscles were studied during biting behavior in the lemon shark, Negaprion brevirostris. High speed cinematography and electromyography of seven cranial muscles were recorded during bites elicited by a probe to the oral cavity. In weak bites mandible depression was followed by mandible elevation and jaw closure without cranial elevation. In strong bites cranial elevation always preceded lower jaw depression, lower jaw elevation, and cranial depression. The average duration of the strong bites was rapid (176 msec), considering the size of the animal relative to other fishes. Different electromyographic patterns distinguished the two forms of bite, primarily in activity of the epaxial muscles, which effect cranial elevation. A composite reconstruction of the activity of seven cranial muscles during biting revealed that epaxial muscle activity and consequently cranial elevation preceded all other muscle activity. Mandible depression was primarily effected by contraction of the common coracoarcual and coracomandibularis, with assistance by the coracohyoideus. Simultaneous activity of the levator hyomandibulae is believed to increase the width of the orobranchial chamber. The adductor mandibulae dorsal was the primary jaw adductor assisted by the adductor mandibulae ventral. This biomechanically conservative mechanism for jaw opening in aquatic vertebrates is conserved, with the exception of the coracomandibularis, which is homologous to prehyoid muscles of salamanders.
Sperm storage and degradation in the spermathecae of the salamander Eurycea Cirrigera
Authors: Sever David M. 
Published: February 2005

AbstractSpermathecae are exocrine glands in the roof of the female cloaca that store sperm. Cytological and histochemical data indicate that the one type of secretion into the lumen is a glycoprotein. After a period of stasis in the summer, production of the secretion is initiated in the fall, coincident with an increase in ovarian follicular size. By the time of maximal follicular development and most intense mating activity in March and April, the spermathecal epithelium is filled with secretory granules. The secretory material is released into the lumen, enveloping the sperm. Many sperm remain in the spermathecae after oviposition, and most of these sperm are degraded in the spermathecal epithelium or pass through interruptions in the spermathecal walls caused by desquamation. Sperm in contact with the stromal environment are phagocytized by leukocytes. Some sperm, however, may survive in the lumen until at least the following fall. These sperm retain normal cytology, but whether or not they remain fertile and intact until a subsequent ovipository cycle is unknown.
Ca++‐ and Na+, K+‐ATPase activities in the fungiform papilla of the tongue of Rana Esculenta (Anura Ranidae)
Authors: Gioglio Luciana , Rapuzzi Giovanni , Quacci Daniela 
Published: February 2005

AbstractIn the fungiform papilla of Rana esculenta (Anura Ranidae), the Ca++‐ATPase is mainly distributed on the basolateral membrane of the sensory area cells (i.e., neuroepithelial, supporting, and mucous cells). Apical membranes of all cells facing the surface present a slight enzymatic activity. Lateral wall cells have a strong Ca++‐ATPase activity on basolateral and apical membranes. Strong Na+, K+‐ATPase activity occurs on the apical surface of neuroepithelial cells. Ca++‐ATPase activity is absent on the surface of endothelial cells of the capillaries located under the sensory area. These observations lead us to conclude that the sensory area of fungiform papilla is the selective way for calcium influx. Furthermore the absence of ATPase activity on the surface of the endothelial cells indicates that there is no functional barrier to calcium influx into capillary, and that calcium can be removed by vessels from the sensory area.
Scanning and transmission electron microscopic observations on the larva of Halicryptus spinulosus (priapulida)
Authors: Storch V. , Higgins R. P. 
Published: February 2005

AbstractThe larvae of Halicryptus spinulosus bear six rings of sensory/ locomotory appendages. Twelve pedicellate flosculi, 6 dorsal and 6 ventral, are associated with the neck–lorica junction. Newly described are two rows of 4–5 flosculi present on the dorsal and ventral plates, and 2 tubuli located on each dorsolateral and ventrolateral plate near their junction with the midlateral plate. The ultrastructure of all organ systems is described. The multilayered lorica differs significantly from that of other priapulids. The anterior fourth of the lorica is not underlain by epidermal cells. At the junction of the introvert and neck are a series of adhesive tubuli that have groups of secretory cells basally. A gland is described at the junction of the fore‐ and midgut.
Structure of the larynx of the tokay gecko (Gekko gecko), with particular reference to the vocal cords and glottal lips
Authors: Moore Beverley A. , Russell Anthony P. , Bauer Aaron M. 
Published: February 2005

AbstractThe ability to vocalize is well‐known in gekkonid lizards but relatively little attention has been paid to the structure of the vocal apparatus. In this study we briefly review the structure of the larynx and associated musculature of the tokay gecko as a baseline for a comparative survey of the family. The cricoid and arytenoid cartilages form the skeleton of the larynx and are controlled by constrictor and dilator muscles. The gross morphology of the vocal cords and glottal lips is then described, the structure being elucidated by way of dissection, histology, and scanning electron microscopy. The vocal cords run between the arytenoid and cricoid cartilages, are highly elastic, and bear a highly folded mucosa. The lips of the glottis have a structure reminiscent of erectile tissue. The respiratory mucosa of the larynx varies according to position and may be related to the tonal aspects of sound production. The structure of the larynx is compared with that of other vertebrates, and the relationship between morphology and phonation is considered.
The interrenal gland of Triturus cristatus after insulin administration during the annual cycle
Authors: LaForgia Vincenza , Capaldo Anna 
Published: February 2005

AbstractThe administration of insulin to Triturus cristatus confirms its action in depletion of the adrenalin (A) granules of the adrenal chromaffin cells and the subsequent activation of phenylethanolamine‐N‐methyltransferase (PNMT). Treatment was carried out in March, when noradrenalin (NA) and A granules are present in almost equal quantities in the chromaffin cells, and in June, when NA granules largely prevail. After insulin administration, adrenalin content of the specimens treated in March decreases from 2.44 granules/μm2 to 0.28 granules/μm2; on the other hand, adrenalin content of the specimens treated in June increases from 0.19 granules/μm2 to 0.31 granules/μm2. These results suggest that in T. cristatus insulin acts both as an adrenalin‐releasing agent and as a stimulator of PNMT activity.
Interrenal of a female gymnophione amphibian, Ichthyophis beddomei, during the annual reproductive cycle
Authors: Masood‐Parveez U. , Bhatta G. K. , Nadkarni V. B. 
Published: February 2005

AbstractThe interrenal (adrenal) of Ichthyophis beddomei lies on the ventral side of the kidney, distributed in four zones. It is separated from the renal tissue by a thin layer of connective tissue and contains both adrenocortical and chromaffin cells. Adrenocortical tissue constitutes a major portion of the interrenal islets; the chromaffin tissue consists of a few cells located at the peripheries of the interrenal islets. Histochemical studies demonstrate the presence of Δ53β‐hydroxysteroid dehydrogenase, 17 β‐hydroxysteroid dehydrogenase, glucose‐6‐phosphate dehydrogenase, succinate dehydrogenase, and sudanophilic lipids in the adrenocortical tissue, suggesting its steroidogenic potential. Annual histometric and histochemical studies show two peaks of interrenal activity: (1) during the breeding phase of the reproductive cycle (January and February) and (2) during the season of heavy monsoon rains (June and July) in the postbreeding phase.
Ultrastructure of somatic tissues in the ovaries of a chaetognath (Ferosagitta hispida)
Authors: Shinn George L. 
Published: February 2005

AbstractTransmission electron microscopy reveals that the ovaries of Ferosagitta hispida contain four somatic tissues. A myoepithelial ovary wall, continuous with a thin layer of peritoneocytes lining the coelomic cavity, encloses a fluid‐filled ovarian space in which oocytes develop. Lamellar extensions of a “follicular reticulum” branch throughout the ovarian space and ensheath developing oocytes. This tissue has been overlooked in most previous studies of chaetognath ovaries. A bipartite oviductal complex extends the length of each ovary just within the lateral ovary wall. It consists of a flattened, blindly ending cellular tube, herein referred to as the cellular sheath, and an enclosed syncytium. Sheath cells secrete an electron‐dense product into the ovarian space. Those sheath cells directly bordering the syncytium are contractile and are joined to the to the syncytium by gap junctions and microvillar interdigitations. The syncytium contains a complex of membrane‐bounded lumina. The latter sometimes enclose sperm received during mating or ovulated eggs. Thus the syncytium serves both as a seminal receptacle and as a duct for passage of eggs to the outside. Contrary to several classical reports, the cellular sheath and syncytium of the oviductal complex do not separate at ovulation to form a temporary oviductal lumen.
Functional osteology of the avian wrist and the evolution of flapping flight
Authors: Vazquez Rick J. 
Published: February 2005

AbstractThe avian wrist is extraordinarily adapted for flight. Its intricate osteology is constructed to perform four very different, but extremely important, flight‐related functions. (1) Throughout the downstroke, the cuneiform transmits force from the carpometacarpus to the ulna and prevents the manus from hyperpronating. (2) While gliding or maneuvering, the scapholunar interlocks with the carpometacarpus and prevents the manus from supinating. By employing both carpal bones simultaneously birds can lock the manus into place during flight. (3) Throughout the downstroke‐upstroke transition, the articular ridge on the distal extremity of the ulna, in conjuction with the cuneiform, guides the manus from the plane of the wing toward the body. (4) During take‐off or landing, the upstroke of some heavy birds exhibits a pronounced flick of the manus. The backward component of this flick is produced by reversing the wrist mechanism that enables the manus to rotate toward the body during the early upstroke. The upward component of the flick is generated by mechanical interplay between the ventral ramus of the cuneiform, the ventral ridge of the carpometacarpus, and the ulnocarpo‐metacarpal ligament.Without the highly specialized osteology of the wrist it is doubtful that birds would be able to carry out successfully the wing motions associated with flapping flight. Yet in Archaeopteryx, the wrist displays a very different morphology that lacks all the key features found in the modern avian wrist. Therefore, Archaeopteryx was probably incapable of executing the kinematics of modern avian powered flight.