摘要:

AbstractThe influence of estrogen on the vasculature of the pars distalis has been studied in two strains of rat that differ in estrogen responsiveness. (Fischer 344 rats are highly estrogen‐responsive in comparison to Sprague‐Dawley rats.) Ovariectomized adults were implanted with silastic capsules containing 17 β‐estradiol benzoate. Control and experimental animals were sacrificed 10 and 20 days after implantation of the silastic capsules.Pituitary weights and plasma prolactin were elevated dramatically in estrogen‐treated Fischer rats in comparison to more moderate increases in Sprague‐Dawley rats. Although both strains exhibited the hypertrophy of mammotrophs expected after estrogen stimulation, the vasculature in Fischer rats was dramatically altered from normal. The pars distalis of the 20‐day, estrogen‐treated Fischer rats contained well‐formed arteries. In addition, capillaries frequently were disrupted, contributing to the formation of hemorrhagic lakes unlined by an endothelium. Even in intact capillaries, basal laminae delimiting the pericapillary spaces often were disrupted or absent. Perivascular connective tissue cells were prominent within the perivascular spaces and often contained rumerous, large lysosomal dense bodies as well as clusters of small dumbbell‐shaped bodies. These granule clusters also were apparent adjacent to the perivascular space within parenchymal cells, most frequently within follicular cells.The vasculature of Sprague‐Dawley rats maintained a more normal appearance after estrogen treatment, although perivascular connective tissue cells did appear activated and basal laminae delimiting the pericapillary spaces were disrupted occasionally. However, no capillaries were disrupted, nor were any hemorrhagic lakes evident, and no arteries were present.The results indicate that in some strains of rat, estrogen may influence the integrity of the pars distalis vasculature, including the possibility of stimulating vascular reorganization and arteriogenesis. If stimulation of arteriogenesis decreases normal hypothalamic inhibition of mammotrophs, this could be an important factor underlying the format

ISSN:0002-9106    

DOI:10.1002/aja.1001790402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractFrom ovulation to oviposition, the corpora lutea of the oviparous lizardsCrotaphytus collarisandEumeces obsoletusexhibit three stages of luteal development: (1) luteogenesis, (2) luteal maturity, and (3) luteal regression. Each stage exhibits distinct characteristics, involving changes in: (1) luteal volume, (2) nuclear diameter of cells within the luteal cell mass, and (3) thecal development. Plasma progesterone concentration is greatest during luteogenesis and is positively correlated with ovarian atresia, although atresia occurred throughout the period of gravidity. These data suggest that in these two species, the corpora lutea secrete high amounts of progesterone immediately following ovulation and exhibit morphologically distinct stages of growth and regression.

ISSN:0002-9106    

DOI:10.1002/aja.1001790403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractGuinea pigs were spayed and given various regimens of injections of estradiol and progesterone. The following were monitored in each animal: pubic separation (relaxin stimulation), resorption of the vaginal membrane (estrogen priming), and the presence of PAS‐positive granules and/or relaxin in endometrial gland cells (EGC). Injections of estradiol alone resulted in resorption of the vaginal membrane, accumulation of PAS‐positive granules in EGC of all animals, and accumulation of relaxin in EGC of two of four animals; but they did not cause pubic separation. Progesterone injections did not result in resorption of the vaginal membrane, separation of pubes, or accumulation of PAS‐positive granules; however, one of three animals demonstrated a few EGC that contained relaxin. Animals that received both estradiol and progesterone exhibited PAS‐positive granules and relaxin in EGC as well as separated pubes, but did not have resorbed vaginal membranes.Upon examination with the electron microscope, EGC from animals that received estradiol alone exhibited remarkable numbers of secretory granules that contained a carbohydrate‐rich material. Secretory granules were not prominent in EGC from animals that received progesterone alone. Estradiol and progesterone injections resulted in accumulation of secretory granules in EGC that contained relaxin and a carbohydrate‐rich material.The observations that estradiol and progesterone induce relaxin production in EGC support the hypothesis that uterine relaxin plays an important role in pregnancy and/or parturition in the

ISSN:0002-9106    

DOI:10.1002/aja.1001790404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractCellular complexes, analogous by virtue of their external appearance, size, and number of seemingly internalized thymocytes to thymic nurse cells (TNCs) of endothermic vertebrates, were seen in short‐term cultures (6–8 days) of mechanically and enzymatically dissociated thymuses of leopard frog tadpoles. Most TNC‐like complexes from mechanically disrupted thymuses were covered with many thymocytes that morphologically resembled the “internalized” thymocytes. With time in culture, most complexes remained spherical and lost their externally adherent and “internalized” thymocytes. Some complexes, however, adhered to the glass substratum by means of macrophage‐like cells. After one typically appearing TNC from a mechanically dissociated thymus had released its “internalized” thymocytes and spread completely over the glass substratum, it could be seen to consist actually of 9–10 stromal cells with the appearance of epithelial cells, macrophages, and dendritic cells. TNC‐like structures from enzymatically dissociated thymuses had few, if any, attached thymocytes. Although these structures closely resembled murine TNCs initially, they displayed abnormal transformations within a few days of culture. Our observations led us to question the assumption that all TNCs from mechanically as well as enzymatically isolated TNCs from vertebrate thymuses are single cells. Rather, some if not all of the so‐called TNC may actually be entities composed of several stromal cell types that enclose thymocytes. We suggest that this configuration seen in vitro may reflect the architecture of the compartmentalized reticular stromal cell meshwork that charac

ISSN:0002-9106    

DOI:10.1002/aja.1001790405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractSpleens of three species of Antarctic seals with different diving habits (Weddell seal, crabeater seal, and fur seal) have been studied with histological, histochemical, and electron microscopic methods. The spleens can be classified as nonsinusoidal, with capsule and trabeculae rich in innervated smooth muscle cells. The trabecular system is particularly well developed in the deep‐ and long‐diving Weddell seal. As in other mammals the pulp can be divided into white and red pulp. In the white pulp, periarteriolar lymphatic sheaths and secondary lymphatic nodules occur; both are surrounded by a marginal zone rich in macro‐phages and eosinophils. The nodules can be observed frequently, which is in accordance with abundance of plasma cells in the red pulp. Well‐developed white pulp and numerous plasma cells and eosinophils obviously reflect a high load of nematodes, which have mainly been found in lung and stomach. Additionally, in the red pulp morphological evidence for the following functions has been found: destruction of erythrocytes, erythropoiesis, and thrombopoiesis. In respect to blood flow through the red pulp, we interpret our observations in the following way: terminal branches of arterioles open into the space between the fibroblastic reticulum cells; blood draining from here is collected into pulp veins, which are mainly found near the trabeculae. Thus, the seals have an open vascular compartment in their spleens, as also occurs in the cat. The red pulp is innervated by numerous nerve fibers that seem to include both cholinergic and adrenergic ones. The target cells of these fibers seem to be the fibroblastic reticulum cells, whose state of contraction may influence the direction of blood flow through the r

ISSN:0002-9106    

DOI:10.1002/aja.1001790406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe surfaces of the brain offer metabolic and mechanical support to the underlying parenchyma. Mouse, rat, and monkey brains were fixed by immersion in a glutaraldehyde fixative or glutaraldehyde with cetylpyridinium chloride, followed by block staining for complex carbohydrates using alcian blue with OsO4postfixation, or OsO4postfixative solution containing ruthenium red, or alcian blue and then ruthenium red‐OsO4treatment. The ependyma in these species had a glycocalyx extending into the ventricular fluid as a finely filamentous network when stained with alcian blue or with alcian blue followed by ruthenium red‐OsO4. Mice in the middle age range had stained material in this glycocalyx resembling the hyaluronic acid reported in the ocular vitreous body. Similar material was seen in the arachnoidal space of these mice and in the inner connective tissue matrix of the dura mater. Both the mouse and monkey had a cell‐free zone, termed the inner dural matrix zone, between the thick fibrous dura and its innermost cellular layer. This zone contained filamentous and globular alcian blue‐stained material. The complex carbohydrates of the mouse ependymal glycocalyx and inner dural matrix zone underwent changes developmentally. Aged rats were injected intraventricularly with latex beads, which, along with extravasated erythrocytes, were seen to adhere to the ependymal glycocalyx. A similar adhesion of erythrocytes was seen in the mouse and monkey ependymal glycocalyx and in the filamentous network of the mouse and monkey inner dural matrix zone.The ependymal glycocalyx, formed in part of complex carbohydrates, is much thicker than previously demonstrated. Some activities related to the ependymal lining of the ventricles, including the movement of cells or particles, the penetration of metabolites or serumprotein fractions (e.g., immunoglobulins), and cell‐surface hydration, probably depend in part on complex carbohydrates that provide a sticky, electrically negative, hydrophilic environment. The complex carbohydrates in the inner dural matrix zone might provide mechanical buffering. Complex carbohydrates in the arachnoidal space may help to maintain a loose tissue that needs not only to be hydrated, but also to be open enough to provide cerebrospinal fluid ci

ISSN:0002-9106    

DOI:10.1002/aja.1001790407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe golden hamster ovarian bursa was studied by light and electron microscopy to clarify the process of its complete closure and the development of lymphatics that leads to morphogenesis of stomata. The results were as follows. (1) The bursa completely closed at 9 days of age primarily due to development of the mesotubarium superius. (2) With the closure, the ovary and bursa became closely apposed, and most of the original bursal cavity disappeared. (3) Between 9 and 12 days of age U‐shaped folds of the bursal mesothelium began to invade the connective tissue of the bursa. (4) Widening of the internal angle of the U‐shaped folds contributed to reappearance of the bursal cavity, and thus separation of the bursa from the ovary. It also contributed to future geometrical proximity of lymphatics to the cavity of the bursa. (5) The separation of the bursa from the ovary began as early as 12 days of age in the cephalic half of the bursa. It occurred remarkably late in the caudal half. Juxtaposition of the window portion of the bursa to the ovary remained in some adult animals. (6) Development of lymphatics in the cephalic half of the bursa was divided into two stages, before and after days 21–24 of life. In the first stage, lymphatics grew in the submesothelial connective tissue, and the framework of lymphatics was formed. In the second stage, lymphatics extended small branches to form the submesothelial plexus or lymphatic lacuna. (7) Intercellular junctions between contiguous lymphatic endothelial cells were mostly tight and desmosomelike. Open junctions were, if they occurred at all, rare. (8) A smooth‐surfaced area lined with the lymphatic endothelium was found in the bursa on day 27 of life, before the initiation of ovulation. Valvelike stomal orifices were absent before the initiation of ovulation and extremely rare even after the first ovulation. They were commonly present in the bursae after the fourth ovulation, however.The process of complete closure of the ovarian bursa is very complex and may be related to the later development of the bursal mesothelium and lymphatics. Some liplike stomal orifices are of purely developmental origin. However, all valvelike stomal orifices are assumed to be formed as a result of damage to the bursal mesothelium, as well as to the submesothelial connective tissue and lymphatics, by repetition of ovulation. It is possible that liplike stomal orifices may be formed in the process of repairing the

ISSN:0002-9106    

DOI:10.1002/aja.1001790408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001790401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY