bluuebunny/crossref_metadata_2025_split huggingface dataset:
The external glial limiting membrane in Macaca: Ultrastructure of a laminated glioepithelium
Authors: Bondareff William , McLone David G. 
Published: February 2005

AbstractThe external glial limiting membrane in Macaca is a multilaminar epithelium‐like mantle formed by the perikarya and interdigitating cell processes of astrocytes. It is separated from the overlying subarachnoid space by a typical basement membrane. Tonofilaments, about 100 Å in diameter, course through the cytoplasm of the processes in sheaths which run in different planes in successive layers of the mantle, forming a course brushwork. Beneath the surface plasma membrane of the superficial astrocytes is a filamentous layer, 500–700 Å thick, which is composed of microfilaments, about 50 Å in diameter. These microfilaments were continuous with the inner aspect of the plasma membrane. The tonofilaments appeared to terminate in the microfilamentous network. The similarity of these microfilaments to the cytocholasin B‐sensitive microfilaments of epithelial cells suggested contractile properties and their participation in the motility of glial cells at the border of the brain and subarachnoid space.
The influence of a prenatal trauma on formation of Purkinje cells
Authors: Andreoli John , Rodier Patricia , Langman Jan 
Published: February 2005

AbstractThe first goal of this investigation was to determine the time of origin of Purkinje cells and their final location in the various lobes of the cerebellum. DUB/ICR mice were therefore injected with several doses of 3H‐thymidine on day 11, 12, 13, 14, or 15 of gestation. Cells formed on days 11 and 12 appeared in all lobes of the postnatal vermis but those formed on day 13 became located mainly in the anterior lobe.The second goal was to examine the effect of 5‐fluorodeoxyuridine, a DNA synthesis inhibitor, on Purkinje cell formation and on repair of the rhombic lip after a prenatal trauma. Five hours after treatment with fluorodeoxyuridine cells with darkly stained nuclear clumps appeared and mitotic activity ceased. Twelve hours after treatment mitotic activity remained low and more affected cells appeared in the neuroepithelium of the rhombic lip. By 24 hours abnormal cells had disappeared, mitotic activity was almost normal and the neuroepithelium had regained its regular continuity. Treatment on day 12 led to a significant deficit of Purkinje cells in all lobes of the vermis, while treatment on day 13 caused a deficit in the anterior lobe only. Despite the postnatal Purkinje cell deficit, compensatory cell proliferation had occurred in the rhombic lip. The mitotic index in the treated embryos reached the value of the controls after 24 hours and was extremely high after 48 hours. Part of this proliferative activity leads to Purkinje cell production, for it was possible to label substantial numbers of Purkinje cells on day 14 of gestation in animals treated with fluorodeoxyuridine on day 12, while control animals have virtually completed Purkinje cell formation by day 14. Although Purkinje cell deficits were accompanied by a reduction in the size of the cerebellum, the cytoarchitecture of the cerebellum appeared normal.
Role of the adrenal cortex in maturation of the lymphoid system and immunological competence; the effects of aminoglutethimide in suckling mice
Authors: Clark Sam L. , Schneider Gary B. 
Published: February 2005

AbstractNewborn rats and mice have rudimentary peripheral lymphoid tissues and are immunologically incompetent. The lymphoid system matures late in the third week after birth, shortly before weaning. The adrenal cortex also is relatively inactive neonatally and begins to secrete glucocorticoids in a mature fashion two weeks after birth. These experiments were designed to test the hypothesis that adrenal glucocorticoids induce maturation of the lymphoid system and immunological competence during the third postnatal week. Mice 10–12 days old were injected daily for 4–11 days with aminoglutethimide, an inhibitor of steroid biosynthesis. The adrenal glands and lymphoid tissues were prepared for histological examination 24 hours after the last injection and evaluated without knowledge of the treatment received. Aminoglutethimide caused adrenal dysplasia with a frequency proportional to dose. Effective doses also inhibited growth, and slightly larger doses were fatal. Therefore it was concluded that large doses of aminoglutethimide caused adrenal insufficiency, but the completeness of this insufficiency in surviving animals was not ascertained. Three phases in postnatal maturation of the lymphoid system were identified by examination of untreated littermate controls and reference to previous work. During the first week after birth, the thymus‐dependent lymphoid tissues grow by immigration of thymus‐derived cells that soon have the capacity for cell‐mediated immunity. During the second postnatal week, a new population of wandering lymphoid cells, presumptively derived from bone marrow, settles in lymphoid organs in response to antigenic stimulation, to form primary lymphoid nodules and a few plasma cells. Late in the third week after birth the machinery for humoral antibody synthesis matures with the appearance of germinal centers and numerous plasma cells, coincident with a great increase in production of immunoglobulin. This third phase of maturation was retarded in mice injected with near‐fatal doses of aminoglutethimide. Because these mice suffered neither involution of lymphoid tissue nor suppression of proliferation in thymus or thymus‐dependent lymphoid‐tissue, it was concluded that the effects of aminoglutethimide upon the development of germinal centers and plasma cells were selective and specific. Therefore these experiments support the hypothesis that glucocorticoid secretion plays a decisive role in maturation of immunological competence during the third week after birth in mice. This role appears to be the potentiation of cellular proliferation and differentiation of B cells in response to antigens, culminating in antibody synthesis. Maturation of adrenal glucocorticoid synthesis has also been implicated in the initiation of physiological involution of the thymus and cessation of intestinal absorption of antibodies during the third postnatal week in rats and mice.
Retrograde perfusions of the pineal region and the question of pineal vascular routes to brain and choroid plexuses
Authors: Quay W. B. 
Published: February 2005

AbstractThe purpose of this study was to experimentally and critically examine the possibility of vascular routes from the pineal gland to the brain in the laboratory rat. Vascular perfusions in the pineal region with India ink in heparinized saline were performed on animals of diverse ages (1 month to 2 years) during the early and middle parts of the daily period of light and immediately post‐mortem. Cleared specimens were studied both before and after serial sectioning for light microscopy. Pineal microvasculature was relatively resistant to retrograde perfusion from the adjacent venous sinuses. But the choroid plexus of the suprapineal recess commonly contained perfusate from these sinuses and the pineal gland.The results define the anatomical limits of possible pineal to brain blood flow, but do not of course provide any direct evidence that such flow exists in vivo. Nevertheless, the results from the perfusions lead to the conclusion that if a direct and non‐systemic vascular path carries pineal hormone to brain, the path consists of the vena cerebri magna and the choroid plexus of the suprapineal recess. This concept assumes reversibility of direction of blood flow in these vessels, an observed physiological property of at least some intracranial veins in other species.
Lateral pterygoid: Two muscles?
Authors: Grant Philip G. 
Published: February 2005

AbstractReinterpretation of existing data and introduction of new evidence appear to indicate that this controversial muscle might better be treated as two muscles. Anatomically the lateral pterygoid in man and in the rhesus macaque has two distinct heads, superior and inferior. Biomechanically, the two heads posses different properties: the superior head has a closing moment (or perhaps no moment) while the inferior head has an opening moment. The findings are similar in the two species. Electromyographically the two heads show different activity patterns: the superior head is active during various jaw‐closing movements only, while the inferior head is active during jaw‐opening and protrusion only. Functionally, therefore, the lateral pterygoid of man and rhesus macaque appears to be two muscles.
Developmental cytology of chromatophores in the red‐spotted newt
Authors: S. Forbes M. , A. Zaccaria R. , N. Dent J. 
Published: February 2005

AbstractThe cytology of pigment‐bearing cells is followed in the integument of the red‐spotted newt, Notophthalmus viridescens viridescens Rafinesque, with observations beginning in the late embryo and continuing through to the adult. Dermal melanophores appear in late tailbud stages, and dermal xanthophores differentiate prior to hatching. In young larvae, both become widely and evenly distributed in the dorsal skin, but in older larvae a pattern develops so that melanophores are absent from certain circumscribed lateral regions designated as melanophore voids. Iridophores differentiate and accumulate among the xanthophores which have remained in the voids. Those xanthophores then are transformed into proerythrophores; that is, their form is altered from stellate to punctate, their nuclei change from fusiform to ovoid, and their pterinosomes are largely replaced by lipid droplets. In some of the voids, the proerythrophores migrate into the epidermis to become the erythrophores of the red spots. The remaining voids cease to exist when their proerythrophores disappear and are replaced by dermal melanophores. At the same time, some dermal melanophores accumulate to form dorsal black spots, and a morphologically different type of melanophore differentiates within the epidermis. In the interspot regions of the eft, xanthophores hypertrophy and pack the dermis, giving an orange color to the skin. In the interspot regions of the adult newt, xanthophores with fewer organelles produce a yellow color on the ventral surface, and, in combination with melanophores and iridophores, produce a greenish color in the dorsum.
Ultrastructural morphology of schwann cell—neuronal relationships in the spiral ganglia of cats
Authors: Jean Adamo Norma , A. Daigneault Ernest 
Published: February 2005

AbstractElectron microscopic study of the cat's spiral ganglia reveals that neuronal cytoplasmic extensions evaginate into the inner Schwann cell lamellae; some may become surrounded by the ensheathing Schwann cell. Inner lamellae of ensheathing Schwann cells penetrate the neuron and invest small portions of neuronal cytoplasm. Membrane‐bound neuronal regions, completely or partially bare of Schwann cell ensheathment, also are observed within neurons or adjacent to the neuronal plasmalemma. Some of these isolated neuronal regions might represent cytoplasmic extensions of the same or another neuron. Speculations are made as to the mechanism by which the observed relationships are formed.
Functional anatomy of the porpoise larynx
Authors: Blevins Charles E. , Parkins Brian J. 
Published: February 2005

AbstractThis paper describes the anatomy of the larynx of an echolocating porpoise and proposes a limited role for that organ in vocalization. Gross dissection of the larynx of the bottle‐nose porpoise Tursiops truncatus reveals the features of component cartilages, muscles and joints. Arytenoid, cuneiform, and corniculate cartilages are present as an incompletely fused cartilaginous unit with each cartilage being identifiable by slight clefts of demarcation. The arytenoid cartilages are freely movable on the cricoid cartilage as a prerequisite for opening and closure of the larynx. Despite the lack of vocal folds to produce a wide range of sounds, it is proposed that the larynx of this species can produce clicks and is partially responsible for whistles.
Pinocytotic activity of the uterus of the rat
Authors: Enders Allen C. , Nelson D. Michael 
Published: February 2005

AbstractWith both scanning and transmission electron microscopy, large ectoplasmic projections are found intruding into the lumen from the epithelial cells of the rat uterus. These projections, which are abundant both prior to implantation and during delayed implantation, communicate with the underlying cytoplasm only by a small pedicel as though in the process of pinching off. However, introduction of tracer material into the uterine lumen demonstrates the pinocytotic nature of these projections. Within three minutes after introduction of tracer the projections, termed pinopods, contain numerous vacuoles filled with tracer. Within ten minutes large vacuoles containing tracer are present in the apical cytoplasm subjacent to the individual pinopods.The varied images observed in the experimental and control materials suggest that there is a continual turnover of pinopods. Initially a simple ectoplasmic projection, the pinopod apparently develops rapidly into a mass of ectoplasm 2–3 μ in diameter with multiple folds and pockets at its surface and numerous internal vacuoles. Following a period of active endocytosis of fluid, the pinopod becomes more spherical and, together with contained material, is withdrawn into the apical cytoplasm.It is suggested that pinocytosis might play a role in producing apposition of the blastocyst to the luminal epithelium, in passing information from the blastocyst to the stroma, and in diminishing the molecular contents of the uterine lumen during specific times in the reproductive process.
Electron microscopic studies of human pituitary tumors. II. Acidophilic adenomas
Authors: Schechter Joel 
Published: February 2005

AbstractNine cases of acidophilic adenoma associated with acromegaly were studied by electron microscopy. The tumor parenchyma contained numerous cells identifiable as somatotrophs, many of which appeared “normalt” and apparently engaged in protein synthesis.In about half of the specimens, there were variations in the electron‐opaque characteristics of the parenchymal cells, most frequently affecting somatotrophs. Characteristic of some somatotrophs was a marked electron‐opacity of the cytoplasmic matrix and nuclear materials, irregular cell contours, hypertrophied cytomembrane systems frequently containing proteinaceous material, and considerable amounts of secretory granules.Disruptions in plasma membranes were apparent throughout the parenchyma, particularly at the parenchymal‐pericapillary interface. This resulted in the release of large numbers of secretory granules and cytoplasmic fragments to pericapillary or extracellular spaces. Small groupings of the disrupted cells often were characterized by scant secretory granules, an electron‐lucent cytoplasmic matrix, and were considered the counterpart of giant multinucleate chromophobes observed with the light microscope.Follicular cells were observed rarely, but when present contained an abundance of fine cytoplasmic filaments and closely resembled follicular cells described in ACTH‐secreting tumors.
The adrenergic cardiac nerves of the cat
Authors: Ellison Jeffrey P. 
Published: February 2005

AbstractA fluorescence method was used for study of the adrenergic cardiac nerves of the cat. Sixteen regions of the heart were examined. The sinoatrial and atrioventricular nodes and the interatrial septum were the most richly innervated regions of the heart. There was little difference between the density of innervation in sections of atrial and ventricular portions of the myocardium. Most of the adrenergic nerves supplying the ventricles were derived from large bundles in the atrioventricular sulcus and were distributed through the subepicardial plexus. Each coronary artery was sparsely innervated in its initial elastic segment, but the vasa vasorum were well innervated. The main trunks of the coronary arteries were surrounded by plexuses composed only of preterminal axons; adrenergic vasomotor terminals were plentiful on the external surface of the muscular media of major and minor myocardial branches. Dense plexuses of adrenergic nerves were seen in both atrioventricular valves. The pulmonary valve was well innervated and contained more adrenergic nerves than the aortic valve. Perivascular plexuses and freely ending adrenergic terminals were observed in the pericardium. Small intensely fluorescent cells were grouped around small blood vessels in the interatrial septum. Most were in the vicinity of the atrioventricular node. It is suggested that these cells, under neural control may secrete catecholamines into the microcirculation of the interatrial septum. They may exert local humoral control over the atrioventricular node or the atrial parasympathetic ganglia.
Prolactin and luteinizing hormone cells of pregnant and lactating rats as studied by immunohistochemistry and radioimmunoassay
Authors: Merchant Frederick W. 
Published: February 2005

AbstractThe objective was to describe the cytological changes that occur in prolactin and luteinizing hormone (LH) cells of the rat hypophysis during pregnancy and lactation and to correlate these changes with secretory activity of the two cell types. The cells were demonstrated with immunohistochemistry and secretory activity was indicated by pituitary and serum hormone concentrations as measured by radioimmunoassay.During pregnancy, two forms of prolactin cells were observed in the pars distalis. One form (prolactin cell I) was small, polyhedral, and constituted most of the prolactin cell population. A second form (prolactin cell II) was found occasionally in pituitary glands of nonpregnant rats and became prominent during pregnancy. It was polyhedral, many times larger than prolactin cell I, and had a restricted distribution in the pars distalis. During gestation prolactin cells I exhibited little change in size, number and staining capacity. Similarly, pituitary and serum prolactin concentrations indicated that the hypophysis releases little prolactin during pregnancy, except for the first few days after conception and before parturition. During lactation, the staining intensity of prolactin cells I and the pituitary prolactin concentration varied little. Prolactin cells II were lightly stained and rare throughout lactation.The staining capacity of luteinizing hormone (LH‐) cells increased as pregnancy progressed in parallel with a rising pituitary concentration of LH during the first half of pregnancy. However, the immunohistochemical procedure appeared to be too insensitive to reflect the gradual fall in pituitary LH concentration during late pregnancy. During early lactation, the reduced staining capacity of LH‐cells was correlated with a low pituitary concentration.
Distribution of calcitonin‐containing cells in the human thyroid
Authors: McMillan Paul J. , Hooker William M. , Deftos Leonard J. 
Published: February 2005

AbstractHuman thyroid glands obtained within 2.5 hours of death were examined for the presence and distribution of calcitonin‐containing cells using horseradish peroxidase as an indicator in an indirect immunohistochemical procedure. The glands were cut into 10 to 20 transverse slices per lobe and fixed in glutaraldehyde. A representative section of each paraffin‐embedded slice was processed and systematically scanned for calcitonin‐containing cells. Of 13 glands examined, ten contained calcitonin cells. The cells were found mostly in the follicular epithelium both singly and in groups. They were most numerous in the central region of each lobe of the gland. The isthmus and poles were devoid of calcitonin cells and only occasionally were these cells found at the surface. Parathyroid glands were examined by the same procedure for the presence of calcitonin cells but none were observed. These results demonstrate that calcitonin‐containing cells are found regularly in human thyroid glands and that the distribution of these cells is centered in the central region of each lobe of the gland.
The cycle of the seminiferous epithelium and spermatogenesis in the bovine testis
Authors: Berndston W. E. , Desjardins Claude 
Published: February 2005

AbstractMorphological changes in the acrosomic system and nuclei of developing spermatids were evaluated as a basis for classifying the stages of the cycle of the seminiferous epithelium in the bovine testis. Light microscopic examination of periodic acid‐Schiff‐stained testicular tissue permitted identification of 14 steps of spermatid development (spermiogenesis). The first 12 steps in this sequence were utilized as the major criterion to divide the cycle of the seminiferous epithelium into 12 distinct stages. Following this, the pattern of germ cell differentiation was investigated by counting the number of germ cells at each stage of the cycle. Based on cell counts, type A spermatogonia divided primarily during stages VII–VIII and IX–X of the cycle. Some type A cells divided again at the end of stage XII to produce intermediate spermatogonia, while others apparently remained “dormant” until the following cycle. At the end of stage IV, intermediate spermatogonia divided to produce type B1 spermatogonia which in turn divided at the end of stage V to produce type B2 spermatogonia. Primary spermatocytes appeared during stage VIII and divided late in stage XI of the following cycle to form secondary spermatocytes. These divided to form young spermatids at the end of stage XII. It was concluded that changes in the acrosomic system and nuclear morphology of developing spermatids provide useful criteria for dividing the cycle of the seminiferous epithelium into stages as well as investigating the pattern of germ cell development during spermatogenesis in the bovine testis.
Formation of central and peripheral myelin sheaths in the rat: An electron microscopic study
Authors: Caley David W. , Butler Albert B. 
Published: February 2005

AbstractFormation of the myelin sheath in peripheral nerve of the newborn rat is compared with its formation in postnatal cerebral white matter. The unmyelinated central axon is bare and myelination begins by the spiral wrapping of an oligodendrocytic process around the axon. The paired membranes of this process fuse on their inside surfaces, lengthen, and spiral around the axon to make a loose sheath of major dense lines. Compact myelin results after fusion of the outside surfaces to form the intraperiod line. Cytoplasm is sparse in developing central myelin, usually being restricted to inner and outer tongues.Unmyelinated peripheral axons are enclosed within a mesaxon formed by the invagination and fusion of the outside surfaces of the Schwann cell plasma membranes. Loose myelin is produced by lengthening and spiralling of the mesaxon (intraperiod line) around the axon. As Schwann cell cytoplasm is extruded from between the spirals, the major dense line forms and compact myelin results. Trapped cytoplasm, a characteristic of developing peripheral myelin, is found in the internodal compact myelin sheath as the inner and outer collars and the Schmidt‐Lanterman clefts.