bluuebunny/crossref_metadata_2025_split huggingface dataset:
The equine spleen: An electron microscopic analysis
Authors: Tablin Fern , Weiss Leon 
Published: February 2005

AbstractThe capacity of the equine spleen to store and rapidly release as much as half the circulating blood volume after adrenergic stimulation depends upon the size of the spleen, its muscular capsule, and the distinctive structure of its red pulp. The unit, or lobule, of red pulp is a cylinder of pulp spaces organized in a reticular meshwork, supplied by a peripheral ring of arterial capillaries, and drained by a central venule. Reticular cells, which make up the meshwork of the pulp, contain an extraordinarily large complement of microfilaments and intermediate filaments and are richly innervated by nerves containing both dense and lucent core vesicles typical of adrenergic nerves. The wall of the pulp venule contains large apertures. The capacious red pulp would thus appear capable both of large‐scale blood storage and, by the contractile adrenergic innervated reticulum and open venous vasculature, of rapid expression of stored blood into the circulation.Antigen‐presenting cells are present not only in B and T cell zones in white pulp but in the periarterial macrophage sheath of red pulp as well. The periarterial macrophage sheath is one of the first sites of antigen capture, and the presence of these cells confers on it an immunological role.
The distribution of cathepsin D in rat tissues determined by immunocytochemistry
Authors: Whitaker John N. , Rhodes Roy H. 
Published: February 2005

AbstractThe distribution of cathepsin D (CD) was surveyed in rat tissues by light microscopic immunocytochemistry. Although immunoreactive CD was detected in all tissues examined, there was a marked difference in the amount in the cytoplasm of different cell types of the same organ. In the retina large amounts of CD were present in the pigment epithelium, ganglion cells, and Müller cells. Moderate to large amounts of CD were also found in neuronal perikarya of the gastrointestinal tract and adrenal medulla; in macrophages in the lung, liver, and spleen; in some secretory cells of the submandibular and lacrimal glands; in parts of renal distal convoluted and collecting tubules; and in the surface transitional epithelium of the calyx, ureter, and urinary bladder. Other cells adjacent to cells containing large amounts of the enzyme had little or no detectable CD themselves. These included hopatocytes, the proximal tubular cells of the kidney, selected cells of the submandibular gland, cells of the zona glomerulosa of the adrenal cortex, and lymphocytes in lymphoid organs. The localization of CD indicates that its degradative effect is exerted preferentially in certain cell types and suggests that physiological influences on CD may have a variety of effects in different organs.
Preantral follicle development during the menstrual cycle in the Macaca mulatta ovary
Authors: Koering Marilyn J. 
Published: February 2005

AbstractOvaries obtained from 18 adult, regularly cycling rhesus monkeys were evaluated to determine the status of preantral follicle development at various stages throughout the menstrual cycle. The ovaries were serially sectioned, and all preantral follicles on every 20th section were classified as developing or atretic, counted and/or measured, and grouped according to size.Results from this study revealed (1) that a significant increase (P < 0.05) occurred in the mean percentage of developing preantral follicles >100 μm in diameter during the periovulatory period, suggesting that follicles in this size range had developed a sensitivity to the unique hormonal milieu present during that stage of the cycle; (2) that similar numbers of primordial and developing preantral follicles were present in the right and left ovaries of a pair, showing that neither ovary had a predominance over the other; (3) that the mean number of developing preantral follicles varied directly with the size of the primordial follicle pool; (4) that atresia was minimal with no significant differences between the various stages of the cycle in any size group; and (5) that polyovular follicles were abundant in certain pairs of ovaries, but could not be related to age or stage of cycle.
Contributions of placodal and neural crest cells to avian cranial peripheral ganglia
Authors: D'amico‐Martel Adele , Noden Drew M. 
Published: February 2005

AbstractThe method of embryonic tissue transplantation was used to confirm the dual origin of avian cranial sensory ganglia, to map precise locations of the anlagen of these sensory neurons, and to identify placodal and neural crest‐derived neurons within ganglia. Segments of neural crest or strips of presumptive placodal ectoderm were excised from chick embryos and replaced with homologous tissues from quail embryos, whose cells contain a heterochromatin marker. Placode‐derived neurons associated with cranial nerves V, VII, IX, and X are located distal to crest‐derived neurons. The generally larger, embryonic placodal neurons are found in the distal portions of both lobes of the trigeminal ganglion, and in the geniculate, petrosal and nodose ganglia. Crest‐derived neurons are found in the proximal trigeminal ganglion and in the combined proximal ganglion of cranial nerves IX and X. Neurons in the vestibular and acoustic ganglia of cranial nerve VIII derive from placodal ectoderm with the exception of a few neural crest‐derived neurons localized to regions within the vestibular ganglion. Schwann sheath cells and satellite cells associated with all these ganglia originate from neural crest. The ganglionic anlagen are arranged in cranial to caudal sequence from the level of the mesencephalon through the third somite. Presumptive placodal ectoderm for the VIIIth, the Vth, and the VIIth, IXth, and Xth ganglia are located in a medial to lateral fashion during early stages of development reflecting, respectively, the dorsolateral, intermediate, and epibranchial positions of these neurogenic placodes.
Follicular growth and kinetics during the estrous cycle, pregnancy and postpartum in the Indian mole rat (Bandicota bengalensis)
Authors: Kaur P. , Guraya S. S. 
Published: February 2005

AbstractFollicular growth and kinetics were studied in detail in the ovaries of the Indian mole rat (Bandicota bengalensis) during various stages of the estrous cycle; days 7, 12, 15, 19, and 21 of pregnancy; and day 2 postpartum. The sizes of follicles, oocytes, nuclei, and nucleoli were measured. In all rats, regression coefficients, a, and intercepts, b, were calculated in oocyte/follicle, oocyte nucleus/follicle and oocyte nucleus/oocyte regressions. The oocyte reached its maximum size when the average follicle diameter was 117 μm in nonpregnant rats and 131 μm in pregnant rats. The oocyte nucleus attained maximum size when the follicle diameter was 110 μm during the estrous cycle and 111 μm during pregnancy and postpartum. Maximum values of the diameter of the largest antral follicle and average diameter of the four largest antral follicles were observed during proestrus (473 and 442 μm, respectively) and on day 21 of pregnancy (611 and 538 μm, respectively). X2 analysis showed that distribution of various types of follicles was not independent of the stage of the estrous cycle and pregnancy. In estrus and metestrus most of the follicles were between stages I and V. However, by diestrus and proestrus, follicles of all size groups developed. The numbers of stage I and II follicles did not differ as pregnancy advanced. More stage V follicles were present on day 12 than on day 7 of pregnancy; however, their numbers decreased by day 15. Afterwards, progressive increase of stage V and (VI + VII) follicles was observed until day 21. This was accompanied by the shift of follicles from stage (III + IV) on days 19 and 21 of pregnancy and even of stage II on day 2 postpartum. Wherever possible, the results have been compared with previous observations in various rodent species.
CSF‐contacting pinealocytes in the pineal recess of the Mongolian gerbil: A correlative scanning and transmission electron microscope study
Authors: Welsh Marcia G. 
Published: February 2005

AbstractThe pineal recess of the Mongolian gerbil was studied using correlative scanning and transmission electron microscopy. The surface of the pineal recess can be subdivided into three distinct zones: (1) central, (2) transitional, and (3) peripheral. In the gerbil, the deep pineal gland is located deep to the central and transitional zones. The ependyma of the peripheral zone is densely ciliated and resembles that of the main ventricular lining. Ependymal cells of the transitional zone are sparsely ciliated but possess numerous microvilli on their apical surfaces. Supraependymal neurons were identified in the transitional zones. These cells appear to make a synaptic‐like contact with the underlying ependymal cells. Of the three zones, the central zone demonstrated the greatest amount of morphological variability. Although a number of supraependymal structures could be identified in the central zone, the most remarkable feature was the presence of protruding cells that possessed no significant surface features Employing correlative transmission electron microscopy, the protruding cells were shown to be CSF‐contacting pinealocytes. The number of CSF‐contacting pinealocytes present in the central zone varied from one cell to large clusters that covered the entire zone. The results of this investigation demonstrate the presence of a direct contact and the potential for interaction between the deep pineal gland and the CSF of the pineal recess in the gerbil.
Comparative study of the arterial and lacunary systems of the ventricular myocardium of elasmobranch and teleost fishes
Authors: Tota B. , Cimini V. , Salvatore G. , Zummo G. 
Published: February 2005

AbstractThe typical fish heart has a spongy trabeculated ventricular myocardium (spongiosa) supplied by the venous blood of the intertrabecular spaces (lacunae); hence it is called a “venous heart.” However, in some fishes a more complex ventricular muscle is found (mixed type), in which the spongiosa is covered by an outer layer of densely arranged myocardial bundles (compacta). The compacta receives oxygenated blood from the coronary vessels. The objective of this study was to investigate relations between myoarchitecture and blood supply with an emphasis on the hitherto unexplored, putative vascular connections between the arterial and the lacunary circuits. Using histological methods combined with vascular cast techniques and India ink injections, it was possible to define four different types of ventricular myocardium and its microvsculature. In some of them an intramural network arises from the subepicardial arterial system supplying the compacta and also is distributed to the spongiosa. Extensive arterio‐luminal vessels connect this coronary bed with the lacunary circuit of the spongiosa, so realizing the first evolutionary step of the Thebesian system. The highest development of these connections is found in some very active pelagic fishes. The functional morphology of these vascuar patterns is discussed in relation to the phylogenetic and functional context of the fish heart. It appears that the concept of the piscine heart as a typical “venous” type is an oversimplified generalization, at least on morphological grounds.
Morphological observations on mucus‐secreting nongoblet cells in the deep crypts of the rat ascending colon
Authors: Altmann G. G. 
Published: February 2005

AbstractIn the ascending colon of adult male rats, large accumulations of differentiated, mucous‐type cells were observed which formed the deep one‐half to one‐third of the crypts almost exclusively. Mitotic activity was localized to the midcrypt, to columnar‐type cells. The mucous‐type cells were designated as “deep crypt secretory” (DCS), and their histological study was initiated. In the light microscope, the apical cytoplasm was distended with mucous vacuoles which stained differently from goblet cells after using periodic acid‐Schiff (PAS), alcian blue, or a Masson stain. In electron‐micrographs, a well‐developed Golgi complex and rough edoplasmic reticulum in addition to a large number of electron‐opaque vacuoles indicated active production of a glycoprotein. The mdcrypt mitotic activity was further demonstrated by using the colchicine technique and 3H‐thymidine radioautography. A gradual increse of mucus content and a decrease of nuclear and nucleolar size in the DCS cells from midcrypt to crypt base indicated that these cells originate in midcrypt and mature as they progress toward the crypt base. Cell counts showed that the number of cells constituting the crypts was about the same all along the colon, but the percentage of DCS cells varied: 33% in ascending and 21% in transverse colon. Only 5% and 8% deep‐crypt mucous‐type cells were found in descending colon and cecum, respectively; but these cells differed in appearance from the mature DCS cells. In conclusion, the presence of a large number of nonmitotic end cells with intense secretory activity has been ascertained for the deep crypts of the ascending colon. The exact relation of these cells to the vacuolated or other epithelial cell types remains for further study.
Three‐dimensional reconstruction of a rat stage V Sertoli cell: I. Methods, basic configuration, and dimensions
Authors: Wong Vivien , Russell Lonnie D. 
Published: February 2005

AbstractA model of a rat stage V Sertoli cell was reconstructed from semiserial sections. Seventy‐five montages were made from 96 grids that supported the 223 sections needed to traverse the reconstructed cell. Section thickness (184.6 nm) and spacing of sections were calculated based on the diameter of spherical germ cell nuclei included within the sections. The outline of the cell border was traced on acetate sheets and from there traced on Plexiglas; then the Plexiglas was cut with a hot wire. The model, enlarged to a magnification of 7,800 times, was made from five parts that may be disassembled. The cell dimensions, as determined from the model, were 89.8 μm in the centripetal axis, 41.2 μm in the longitudinal axis, and 29.5 μm in the circumferential axis. The cell was irregularly columnar in shape with a base resting on the basal lamina and lateral surfaces in contact with adjacent Sertoli cells and round germ cells. Lateral processes were of three types: (1) conical processes extending from the lateral surface near its base; (2) cup‐shaped, sheet‐like processes partially encompassing round germ cells; and (3) flattened, sheet‐like processes extending between round germ cells. Elongate spermatids occupied deep, irregularly shaped cylindrical recesses oriented in the centripetal axis of the Sertoli cell. The walls of the Sertoli cell forming these cylinders were thick basally and sheet‐like and very thin near the lumen where they anastomosed and also composed the lateral walls of the cell. The tapered luminal extensions of the sheet‐like, cylindrical processes were termed apical processes. The volume of the reconstructed cell was calculated to be 6,012 μm3. This study has provided the first unencumbered view of the external profile of a Sertoli cell. The model represents one of two major configurations that the Sertoli cell assumes during the spermatogenic cycle.
Three‐dimensional reconstruction of a rat stage V Sertoli cell: II. Morphometry of Sertoli–Sertoli and Sertoli–germ‐cell relationships
Authors: Weber James E. , Russell Lonnie D. , Wong Vivien , Peterson R. N. 
Published: February 2005

AbstractSertoli–Sertoli and Sertoli–germ‐cell configurational relationships were studied using morphometric techniques and direct measurements as obtained from micrographs used to reconstruct a model of a rat stage V Sertoli cell. Regional areas of the Sertoli cell surface, which faced germ cells, other Sertoli cells, or noncellular structures, were expressed as relative surface area percentages; and the absolute surface areas for these regional areas were calculated. The surface area of the reconstructed cell, in its unmagnified state, was found to be 12,163 μm2. Cell processes were enumerated and studied using morphometric techniques. The surface area of the reconstructed Sertoli cell facing germ cells and Sertoli cells was also determined. Five Sertoli cells showed extensive contact with the reconstructed cell at the level of the Sertoli‐Sertoli junctional contact region. This contact region averaged 3.51 μm in width. The relative and absolute surface area of subsurface ectoplasmic specialization of the Sertoli cell that faced germ cells and other Sertoli cells was calculated, and the extent of penetration of step 17 spermatids into the Sertoli crypts was determined. Surface relationships of the reconstructed cell to cellular and noncellular elements were depicted on outline drawings of the Sertoli cell.
Some observations on the structure of Suncus liver with special reference to the vitamin A‐storing cell
Authors: Matsumoto Emiko , Hirosawa Kazushige 
Published: February 2005

AbstractThe structure of the liver of the thick‐tailed shrew (Suncus murinus) was studied with special reference to the vitamin A‐storing cell. The macroscopic arrangement of hepatic lobes was the same as those of rodents. Connective tissues of Glisson's sheath were not prominent. There were gradual differences in the size and the cytoplasmic contents of hepatocytes among perihepatic, intermediate, and periportal regions. These correspond to the acinar zones 3, 2, and 1 of Rappaport, respectively. The ultrastructural features of the hepatocyte were numerous microvilli, a large mass of glycogen particles (α‐particles), and well‐developed Golgi complexes and lysosomes in the peribiliary region. Cellular elements of the sinusoid were the same as those of rodents.Vitamin A‐storing cells were demonstrated by autoradiography of tritiated retinyl acetate administered orally. They were distributed in the perihepatic and intermediate regions. The number of vitamin A‐storing cells was much smaller than that in the mouse liver and did not increase after excess vitamin A was given to the animal. Cytological features of the vitamin A‐storing cells in Suncus liver were similar to those for other mammalian livers. The scarceness of vitamin A‐storing cells and the low amount of vitamin A esters suggest that Suncus does not store much vitamin A in the liver.
Synaptic changes in the hypothalamus of the prepuberal female rat administered estrogen
Authors: Clough Richard W. , Rodriguez‐Sierra Jorge F. 
Published: February 2005

AbstractSubcutaneous administration of estradiol benzoate (EB) to prepuberal female rats can advance vaginal opening, phasic pituitary gland luteinizing hormone (LH) secretion, and ovulation, presumably through a neural mechanism. This study investigated whether these effects are associated with changes in synaptic profiles in the arcuate nucleus of the hypothalamus (ARC) and the preoptic area (POA). Twenty‐five‐day‐old female rats were adminstered EB, EB followed by progesterone on day 27, or oil vehicle alone; or they received no treatment. Blood was collected by jugular venipuncture at 1600 hr, on day 27, and plasma was assayed for LH by radioimmunoassay. Rat brains were immediately perfused for electron microscopy, and the ARC and POA were dissected out. Tissue blocks from these areas were processed with phosphotungstic acid for selective staining of neural synapses. Serum LH was markedly elevated in the EB‐treated rats compared with controls. In the treated groups, LH values in serum were above 1,000 ng/ml, whereas the control values were less than 50. This acute rise of serum LH was accompanied by an acute increase of synaptic volume percent, area density, and numerical density in the ARC of EB‐treated rats. The numerical density of the control groups was approximately 800 million observed synapses per cubic millimeter, whereas in the EB‐treated groups, there were approximately 1.8 billion synapses per cubic millimeter. We found no differences in synaptic profiles of the POA in EB‐treated animals as compared to the controls. We conclude from this study that estrogens act through neural mechanisms to accelerate maturation of neuroendocrine processes that govern phasic pituitary gland LH release and that this maturation process entails synaptogenesis in the ARC.
Pattern regulation in the anterior half of the embryonically produced symmetrical forelimb of the axolotl, Ambystoma mexicanum
Authors: Tank Patrick W. 
Published: February 2005

AbstractSymmetrical forelimbs were created in the axoltl by performing surgery on embryos at stages 32–34. The technique of J. M. W. Slack (J. Embryol. Exp. Morphol., 39:151–168, 1977) was utilized. Several experiments were then performed to test the ability of thesesymmetrical forelimbs to participate in pattern formation. When symmetrical limbs were amputated without previous surgery, 58% failed to regenerate. When symmetrical limbs were wounded in the plane of symmetry and permitted to heal for 30 days prior to amputation, 75% failed to regenerate. When the anterior half of the symmetrical limb was exchanged with the posterior half of the contralateral forelimb followed by amputation 30 days later, both limbs failed to regenerate. When the anterior half of the symmetrical limb was exchanged with the anterior half of an asymmetrical limb followed by amputation 30 days later, the previously symmetrical limbs regenerated asymmetrical hands, and previously asymmetrical limbs failed to regenerate. These results indicate that wounding increases the occurrence of regenerative failure in embryonically produced symmetrical forelimbs. The anterior half of the embryonically produced symmetrical forelimb behaves unpredictably and in a manner not easily described with any of the current models of pattern regulation. The posterior half of the embryonically produced symmetrical forelimb behaves predictably during pattern formation.
Retrograde hrp identification of neurons in the rhombencephalon and spinal cord of the rat that project to the dorsal mesencephalon
Authors: Morrell J. I. , Pfaff D. W. 
Published: February 2005

AbstractNeurons in the rhombencephalon and spinal cord of the rat that project to the dorsal midbrain were identified using the HRP retrograde neuroanatomical tracing method. Retrogradely labeled neurons were most numerous in the reticular formation, specifically in nucleus pontis oralis, caudalis, and gigantocellularis and in the sensory trigeminal complex. Neurons that project were also found in certain raphe nuclei, the parabrachial nuclei, the deep cerebellar nuclei, the vestibular cochlear complex, and the spinal cord.The diverse distribution of neurons that project to the midbrain is understandable in the context of the known diverse functions of the region, which include a role in sexual and other behaviors, nociception, and various autonomic functions.