bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of steroids on definitive localization of primordial germ cells in the chick embryo
Authors: Swartz William J. 
Published: February 2005

AbstractIt has been suggested that PGCs are attracted to developing gonads by a chemotactic‐like agent secreted by the gonads and that this agent might be steroidal in nature. This study was undertaken to ascertain whether specific exogenous steroid hormones exert an influence on germ cell colonization of the gonads, by enhancing, inhibiting or otherwise interfering with it. Testosterone cypionate in cottonseed oil, crystalline testosterone propionate, estrone in aqueous suspension and crystalline estradiol‐17β were administered to chick embryos at 33 hours incubation. Normally developed embryos, those receiving cottonseed oil (vehicle for testosterone cypionate) and those receiving cholesterol served as controls. A decrease in the number of germ cells in the gonadal area at five days of incubation occurred in all groups receiving the androgens and estrogens. However, in only one group (that receiving testosterone cypionate) was this decrease found to be significant. The mean number of germ cells found in the cottonseed oil controls and the cholesterol controls closely paralleled that of the normally developed controls. Normal asymmetry in the distribution of the germ cells favoring the left side in the chick was not affected in any of the groups; however, the percentage distribution of the germ cells between the right and left gonads at this early stage appeared to be affected.
The mode of lymphocyte migration through postcapillary venule endothelium in lymph node
Authors: Farr Andrew G. , De Bruyn Peter P. H. 
Published: February 2005

AbstractThe pathway of migration of lymphocytes across the walls of the postcapillary venules was studied in lymph nodes of rats. By means of serial sections, it was determined that lymphocytes enter the venule wall through the endothelial cells and not through the intercellular spaces. After the endothelial cell has been penetrated, the lymphocytes enter the intercellular spaces, from where they gain access to the lymphatic parenchyma. It cannot be excluded, however, that in some instances the path of migration of a lymphocyte is entirely through an endothelial cell from lumen to subendothelial space. While perforating an endothelial cell, a migrating lymphocyte may be in simultaneous contact with the vascular lumen, the intercellular space, and the subendothelial tissue.
Development of the implantation chamber in the pregnant bitch
Authors: Barrau Marny D. , Abel John H. , Torbit C. A. , Tietz W. J. 
Published: February 2005

AbstractUteri taken from 25 bitches at various times during the early stages of pregnancy were studied cytologically to determine how the implantation chamber developed and how fetal‐maternal relations were established. On day 13 after the end of estrus, knobs of trophoblastic syncytium formed and became wedged between cells of the uterine luminal epithelium. The syncytium quickly spread along the uterine lumen and into the mouths of the glands, dislodging and surrounding maternal cells. As invasion continued trophoblastic villi, consisting of cores of cytotrophoblast covered by a continuous layer of syncytium, penetrated deeper into the endometrium. The syncytium spread to surround maternal vessels and decidual cells. By day 26 the trophoblast had extended down to the large lacunae. Here syncytial trophoblast covering tips of the villi degenerated, leaving cytotrophoblast exposed to the necrotic zone. These cells possessed characteristics of absorbing cells. Hematomas were formed by focal necrosis of fetal and endometrial tissue at the poles of the implantation sites. Large pools of extravasated blood accumulated and red blood cells were phagocytized by surrounding trophoblastic cells.Therefore, the endotheliochorial relationship in the canine placenta appeared to be established by syncytial trophoblast invading a cellular endometrium. In the necrotic zone and hematomas, cellular trophoblast may have lost its syncytial covering, but elsewhere maternal vessels and decidual cells in the placenta were in direct contact only with syncytial trophoblast.
Cytodifferentiation of striated duct cells and secretory cells of the convoluted granular tubules of the rat submandibular gland
Authors: Cutler Leslie S. , Chaudhry Anand P. 
Published: February 2005

AbstractThe structural and functional development of the striated ducts and convoluted granular tubules (CGT) of the rat submandibular gland (SMG) were studied by electron microscopy and alkaline protease chemistry. Development of the SMG was followed from 14 days of gestation through 30 weeks of age. The specialized morphology of the basal aspect of the striated duct cells arises from cellular extensions which are first seen at 20 days of gestation. These processes elongate and intertwine with similar processes from adjacent cells, and as the cells enlarge the processes are compressed together giving the appearance of “infolding” of the basal plasma membrane. Mitochondria migrate to the basal part of the cell and are seen in close relationship to the cellular extensions throughout the development of these cells. Development of the striated duct is complete by one week after birth. The CGT develop from the proximal portions of intralobular striated ducts. At one week after birth, cells of the proximal striated duct demonstrate apical vacuoles. By two weeks after birth these vacuoles are replaced by distinct zymogen‐like granules. There is a progressive accumulation of large numbers of secretory granules in the CGT cells as the animals age. However, rough endoplasmic reticulum is a relatively inconspicuous cellular component throughout development. The accumulation of alkaline protease activity in the gland closely parallels the pattern of granule accumulation.
A light and electron microscopic study of the pineal gland of the ground squirrel, Citellus tridecemlineatus
Authors: Povlishock John T. , Kriebel Richard M. , Seibel Hugo R. 
Published: February 2005

AbstractThe pineal gland of the 13‐lined ground squirrel (Citellus tridecemlineatus) has been examined at the light and electron microscopic level. This gland is composed of low‐density parenchymal cells interspersed among which are occasional glial, vascular and neural elements. Punctuating the glandular parenchymal mass are prominent perivascular and intercellular spaces.The parenchymal cells possess numerous mitochondria and less prominent profiles of rough and smooth‐surfaced endoplasmic reticulum. Golgi apparatus, microtubules and lipid droplets of varying size and electron density constitute regular cytoplasmic features, with dense‐core vesicles being present occasionally. The parenchymal cells have numerous processes. One among these in each cell extends for several micra to terminate in a bulbous expansion containing both clear and dense‐core vesicles and occasional electron‐dense inclusions. These bulbous terminals are found within the perivascular and intercellular spaces where they course in close proximity to both other parenchymal elements and axon terminals. Glial cells and their processes invest the pineal periphery and incompletely separate the parenchymal cells.
Neuroanatomical clues to peripheral locomotor control in small crustaceans (Artemia salina)
Authors: Kane Eileen S. C. 
Published: February 2005

AbstractBrine shrimp (Artemia salina) were prepared for light and electron microscopy at several stages. Immersion‐fixed, rapid Golgi impregnations demonstrated two distinct neuronal types in thoracic appendages of mature, freely swimming Artemia. Isolated motor neurons had large cell somas and thick, radiating dendrites at the body wall‐limb junction. A long, elaborate axon extended into the limb. Groups of a second type of neuron with smaller somas and very thin, radiating processes occurred in the distal limb near presumably tactile bristles. Thick axons from motor neurons were traced to terminals associated with limb muscle. Both muscle and axon were best seen with Nomarski optics. Motor axons possessed elongate, irregularly shaped boutons en passant and morphologically variable boutons terminaux; the latter included huge endings with knobbed projectiles arising from thick collaterals, or smaller, round boutons from thin collaterals. In addition, a thick, unidentified axon coursed longitudinally within the central body wall, sending short collaterals peripherally. The elaborate peripheral neurons described in this Golgi study may be anatomical correlates for the extraordinary coordination of mature brine shrimp. Because Artemia movements resemble those of leech and decapods, which have been studied extensively electrophysiologically, the possibility of similarly elaborate peripheral structures supplementing central control of locomotion in those invertebrates should be considered.
Organ culture of osteopetrotic (ia) rat bone: Evidence that the defect is cellular
Authors: Nyberg Leroy M. , Marks Sandy C. 
Published: February 2005

AbstractCalvarial bone from osteopetrotic (ia) rats and normal littermates has been cultured in a chemically defined medium supplemented with homologous serum to test for the presence of inhibitors or the absence of promoters of bone resorption in mutant serum. In addition, the response of mutant and normal bone to parathyroid extract and hydrocortisone was tested in vitro. The results indicate that mutant and normal serum do not differ with respect to their ability to support bone resorption and that ia bone responds to hydrocortisone but not parathyroid extract in organ culture. These data indicate that the skeletal defect in ia rats is not humoral but cellular.
Ultrastructural evidence for the uptake of 5,6‐dihydroxytryptamine in the frog's gustatory cell
Authors: Nada Osami , Hirata Kazuho 
Published: February 2005

AbstractThe fungiform papillae of the frog were examined electron microscopically after a single injection of 5,6‐dihydroxytryptamine (5,6‐DHT). Thirty minutes after 5,6‐DHT injection, numerous vesicles partially occupied with dark material were found in the cytoplasm of gustatory cell processes. Three days after the drug treatment, the majority of vesicles were completely filled with dark material so that their limiting membrane became obscure, while the terminal portions of gustatory cells showed no evidence for fine structural alteration indicative of drug retention. In addition, clear vacuoles, suggesting a degenerative change induced by the uptake of the neurotoxic agent, occurred in the cytoplasm of gustatory cell processes. It is suggested that the uptake of 5,6‐DHT in gustatory cells may reflect the presence of an indoleamine, probably 5‐hydroxytryptamine (serotonin).
Intercellular relationships in the external glial limiting membrane of the neocortex of the cat and rat
Authors: Williams Vick 
Published: February 2005

AbstractThe external glial limiting membrane of the cerebral cortex appears to be a complete astrocytic mantle covering the pial surface of the molecular layer. It consists of flattened cell bodies arranged singly or in small groups spaced about 100 μ apart and multitudes of interdigitating processes arrayed in layers. The glial mantle is thicker in the sulci than on the gyri. It is covered externally by a basal lamina which is associated with collagenous fibrils and cells of the pia mater. The extracellular space in aldehyde‐perfused material appears as a regular, electron‐lucent interval 150 Å wide between adjacent cell membranes. Gap junctions are frequently encountered in the external glial limiting membrane; desmosomes are present between astrocytic processes but are seen much less often.
The hypothalamic magnocellular neurosecretory system of the guinea pig. II. Immunohistochemical localization of neurophysin and vasopressin in the fetus
Authors: Silverman A. J. 
Published: February 2005

AbstractThe development of the hypothalamic magnocellular neurosecretory system of the fetal guinea pig was examined by immunohistochemistry. Neurophysin was first observed in the supraoptic nucleus (SON), median eminence (ME) and posterior pituitary (PP) on day 40 of gestation. It was not regularly present in the paraventricular nucleus (PVN) until day 47. Vasopressin was first observed in the SON, ME and PP on day 45. In the median eminence immunoreactive deposits indicative of both peptides were observed in both the fibers of the hypothalamo‐hypophysial tract (H‐HT) in the presumptive zona interna as well as in axons projecting to the developing primary portal plexus.
Proliferative kinetics of large and small intraepithelial lymphocytes in the small intestine of the mouse
Authors: Röpke C. , Everett N. B. 
Published: February 2005

AbstractThe proliferative kinetics of the intraepithelial lymphocytes (IL) of the mouse intestine have been evaluated. By inducing mitotic arrest it was found that large IL — constituting about 50% of the IL — showed a mitotic rate of 2.3. Autoradiographic results obtained after two different schedules of 3H‐thymidine injections showed that 30% of the large IL were in DNA synthesis, and that the large IL were renewed at a rate comparable to that of blast cells from Peyer's patches, mesenteric lymph nodes and thoracic duct lymph. The small IL were renewed very rapidly compared to small lymphocytes of peripheral lymphoid tissues, although small lymphocytes with lifespans of several weeks were also present in the epithelial sheet. By the use of intestinal perfusion, in vivo, it was estimated that the loss of lymphocytes from intestinal villi into the lumen of the gut was negligible, and it is concluded that the most probable kinetic model for the majority of IL is: B and T lymphoblasts invade the epithelium and undergo mitosis. B lymphoblasts give rise predominantly to plasma cells, and T lymphoblasts give rise to small lymphocytes — probably long‐lived — which reenter the circulation.
The effects of preparative procedures for scanning electron microscopy on the size of isolated lymphocytes
Authors: Schneider Gary B. 
Published: February 2005

AbstractThe diameter of lymphocytes, isolated from a sample of peripheral blood by Ficoll‐Hypaque sedimentation, was determined after eight different steps in the preparative procedure for scanning electron microscopy (SEM). There was a 43% total reduction in mean cellular diameter of the lymphocytes studied, the diameter dropping from 8.4 μm prior to fixation, to a final diameter of 4.8 μm in the cells examined under the scanning electron microscope. The bulk of this shrinkage occurred during critical‐point drying. In view of this finding, caution should be exercised in describing detailed cell surface morphology by SEM when similar preparative procedures are employed.
Descending inputs to caudal cochlear nucleus in cats: A horseradish peroxidase (HRP) study
Authors: Kane Eileen S. 
Published: February 2005

AbstractAfter HRP injections into the octopus cell area of the cat cochlear nucleus, only periolivary neurons of the superior olivary complex (SOC) reacted. Elongate neurons in the lateral periolivary nuclei (ipsilateral to the injection) and multipolar neurons in ventromedial periolivary regions (contralateral to the injection) contained granules. No neurons in the main SOC nuclei or higher auditory nuclei reacted, despite a wide range of HRP concentrations. Thus, neurons from the SOC to the octopus cell area of the cochlear nucleus seem to be entirely periolivary and not entirely equivalent to neurons providing collaterals to the olivocochlear bundle.
Tannic acid as an electron‐dense probe in the testis
Authors: Aoki Agustin , Einstein Jill , Fawcett Don W. 
Published: February 2005

AbstractThe use of tannic acid to preserve and promote the staining of protein constitutents of the extracellular fluid is described. Its usefulness for delineating the extracellular compartment and detecting changes in capillary permeability is illustrated in experiments on the testis.
Myelinated nerve cell bodies in the dorsal horn of the monkey (Saimiri sciureus)
Authors: Beal John A. , Cooper Margaret H. 
Published: February 2005

AbstractWhile observing electronmicroscopic preparations of laminae I–III of Rexed (1952), taken from the lumbosacral region of squirrel monkey spinal cord, several small neuronal cell bodies were found which were partially or completely encircled by compact myelin sheaths of varying thickness. Though found in all three laminae, the occurrence of these perikaryal sheaths was less frequent in the “inner zone” of lamina II where there were few myelinated fibers. Perikaryal profiles which were completely surrounded by myelin exhibited neither internal mesaxons nor external tongue processes and the origin of their myelin is obscure. In cases of partially enveloped cells the myelin was often clearly derived from extensions of myelin sheaths surrounding small‐diameter axons. These overgrowths of myelin extended away from their axons at a pole near their internal mesaxon and spread out across the surface of neighboring nerve cells. In some cases the extensions were derived from the entire axonal sheath while in others only the external lamellae were included. The external tongue process, when observed, was located at the distal end of the axonal myelin extension. Overgrowths of axonal myelin which were unrelated to neuronal cell bodies were also found but these formations were less extensive.
Electron microscopic immunohistochemical localization of vasopressin and neurophysin in the median eminence of normal and adrenalectomized rats
Authors: Dube Donald , Leclerc Rachel , Pelletier Georges 
Published: February 2005

AbstractUsing an immunoperoxidase technique at the ultrastructural level, vasopressin (VP) and neurophysin (NP) were localized in the axons of the median eminence of normal and adrenalectomized rats. Whereas VP and NP were generally found in 150‐nm granules in the internal zone of the normal rat median eminence, in the adrenalectomized rat, many granules of about 80 to 100 nm in diameter were found to contain NP and VP in the external zone of the median eminence.
Formation of packaging units in cricket late spermatid nuclei as visualized by spreading techniques
Authors: Tres Laura L. , Kierszenbaum A. L. 
Published: February 2005

AbstractThe nuclear organization of a particular step of cricket late spermiogenesis was examined by an electron microscope study of spermatids dispersed by air‐liquid surface tension. Cell spreading techniques facilitate a display of condensing spermatid nuclei sufficient to allow interpretation of chromatin packaging processes. Results indicate that nuclei of late developing cricket spermatids are integrated by multiple packaging units as the result of an orderly aggregation of individual chromatin fibers. Each packaging unit consists of a thick fascicle, formed by the alignment of smooth chromatin fibers, which frays out into tassels of looped fibers.
The systemic arterial pattern of the guinea pig: The pelvis and pelvic limb
Authors: Stump John E. , Shively Michael J. 
Published: February 2005

AbstractThe systemic arterial pattern of 59 guinea pigs was examined by dissection, angiography, or corrosion casting. The blood supply to the pelvis and the pelvic limbs arises as two terminal branches of the aorta, the right and left common iliac arteries, and each of these divides into external and internal iliac arteries. Their pattern of distribution resembles a typical mammalian pattern. The external iliac artery passes through the body wall to supply the pelvic limb and the internal iliac artery is distributed primarily to the pelvic region and its viscera.
Melatonin induction of testicular recrudescence in hamsters and its subsequent inhibitory action on the antigonadotrophic influence of darkness on the pituitary‐gonadal axis
Authors: Reiter Russel J. , Vaughan Mary K. , Rudeen P. Kevin , Philo Ronald C. 
Published: February 2005

AbstractExposure of adult male hamsters to light‐dark (LD) cycles of 0:24 (in hours) for 12 weeks induced atrophy of the testes and accessory sex organs and a drop in immunoreactive pituitary and plasma prolactin levels. The subsequent exposure of these hamsters to LD 14:10 cycles caused regeneration of the sexual organs and an increase in pituitary LH and prolactin levels. Likewise, the weekly treatment of dark‐exposed hamsters with subcutaneous melatonin‐beeswax pellets led to regeneration of the peripheral reproductive organs and an increase in pituitary LH and prolactin levels. After gonadal regeneration, complete darkness failed to induce atrophy of the reproductive system indicating that either long photoperiods or melatonin treatment cause the pituitary‐gonadal axis to be refractory to the inhibitory influence of darkness.
The fine structure of the digital corpuscle of the mouse toe pad, with special reference to nerve fibers
Authors: Idé Chizuka 
Published: February 2005

AbstractDigital corpuscles in the dermal papillae of the mouse toe pad have been studied using light and electron microscopy of serial thick and thin sections, and silver impregnations of frozen sections. These corpuscles are ellipsoid in shape and approximately 10–30 μm in diameter. They consist of one to three lamellar cells, nerve fibers and a capsule. These digital corpuscles are regarded as small Meissner corpuscles. The capsule is perineural epithelium. One or two myelinated nerve fibers and occasionally an unmyelinated nerve fiber enter the corpuscle. The axon terminals contain many mitochondria and a variable population of vesicular profiles. These terminals are ellipsoid or discoid in shape with the long axis parallel to the skin surface. The cytoplasmic plates (or lamellae) of the lamellar cells are arranged parallel to the skin surface, as is the cleft between the bilaterally symmetrical stacks of lamellae. Small processes extend from the expanded terminal of the neurite into the cleft between the lamellae. The relationship of the neurite terminal and associated lamellar cells resembles in some respects the organization of the inner core of Pacinian corpuscles. Intraepidermal fibers derived from myelinated neurites of the corpuscle may extend to the superficial epidermis. Intraepidermal fibers derived from unmyelinated neurites usually terminate in the basal regions of the epidermis.
Effects of Rous Sarcoma Virus on the synthetic programs of chondroblasts and retinal melanoblasts
Authors: Roby K. , Boettiger D. , Pacifici M. , Holtzer H. 
Published: February 2005

AbstractChondroblasts and retinal melanoblasts have been transformed with a temperature‐sensitive Rous Sacroma Virus. At permissive temperature the transformed cells do not display their unique phenotypic properties. When such transformed cells are shifted to non‐permissive temperature they do display their unique phenotypic properties.
Identification of challenged subarachnoid free cells
Authors: Merchant Randall E. , Low Frank N. 
Published: February 2005

AbstractThree distinct types of free cell contours are recognizable in scanning electron microscopy (SEM) on the leptomeningeal sheaths of dogs twelve days after an intrathecal injection of bacillus Calmette‐Guerin (BCG). Macrophages possess abundant plasmalemmal blebs which are shown in transmission electron microscopy (TEM) to be composed of large membrane‐bound vacuoles. Smooth surfaced lymphoblasts exhibit many basal microvilli that rest upon and often indent the plasmalemma of an underlying pial cell. Neutrophils display many microvilli over their rounded, chrysanthemum‐like surfaces. The consistency with which these external features are expressed suggests that each cell type possesses characteristic surface topography, at least under these conditions of challenge.