摘要:

AbstractThe paucity of information on the early developmental stages and the necessity for re‐evaluation of the phylogenetic implications of the tupaiid fetal membranes have stimulated the present study.Neonatal tupaiids possess prominent bilateral endometrial pads that run the length of each uterine horn. These gland‐free pads are the sites of implantation and placentation in adults. Implantation is bilateral and superficial. Multinucleated giant cells differentiate from the cytotrophoblast of the attachment sites; they facilitate the marginal expansion of the placental disc by detaching the paraplacental epithelium from its basement membrane.Prominent bilateral chorio‐vitelline placentae develop and remain functional through early limb bud stages. Decidual cells fuse to form “decidual knots” during this period.The bilateral chorio‐allantoic placentae are labyrinthine endotheliochorial. The trophoblast of the labyrinth is entirely syntrophoblastic, similar to the condition in the armadillo placenta. Epithelioid mesenchymal cells in the labyrinth are strikingly similar to those of the shrew placenta. The large allantoic vesicle and free vascular yolk sac persist. Amniogenesis occurs by folding.Uterine glands remain secretory throughout pregnancy; iron is probably supplied to the fetus in

ISSN:0002-9106    

DOI:10.1002/aja.1001230302

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

年代:1968

数据来源: WILEY

摘要:

AbstractDaily subcutaneous injections of cortisone acetate (0.5, 1.5 or 2.5 mg) were given to three groups of mice for seven consecutive days. Daily systolic blood pressures of the anesthetized mice were obtained by adapting the method of Friedman and Freed ('49). The maximal arterial pressure increase for the 0.5, 1.5 and 2.5 mg groups was 22%, 31% and 41% respectively. This supports the conclusion that cortisone produces hypertension in mice when administered in large doses. Mural hyalinization, vacuolization and cellular proliferation of coronary arteries were greatest in the 0.5 mg group. The highest incidence of myocardial necrosis, 56%, was in the group receiving 2.5 mg of cortisone daily. The frequency and severity of myocardial and renal cortical necrosis were directly related to the size of the cortisone dose. Adrenal medullary vacuolization and lipid infiltration of the liver were common in all experimental groups.

ISSN:0002-9106    

DOI:10.1002/aja.1001230303

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

年代:1968

数据来源: WILEY

摘要:

AbstractIn terms of their light microscopic appearance and fine structure the ovarian interstitial cells of the rabbit are typical steroid‐secreting cells. They are characterized by an abundance of agranular endoplasmic reticulum, spherical mitochondria with closely packed lamellar cristae, lipid droplets which appear to arise independently of the endoplasmic reticulum, conspicuous Golgi areas, a cytoplasm containing ribosomes and variable numbers of glycogen granules. A feature of the differentiation of the cells from the theca interna of atretic follicles or the stroma is the enlargement of the multiple Golgi areas and the progressive accumulation of agranular endoplasmic reticulum, possibly by “budding” from the Golgi cisternae. “Light” and “dark” cells are observed, the latter being characterized by a more closely packed agranular endoplasmic reticulum which tends to be tubular in type, that of the “light” cell being vesicular. Electron dense material (lipid?) is found in the vesicles and tubules of the agranular endoplasmic reticulum and in the Golgi cisternae; it may indicate a role of these structures in the biosynthesis of steroidal hormone. No fine structural changes specifically associated with pregnancy were observed. Degenerative changes are common and are described. The role of the interstitial cells, especially in relation to the production of 20 alpha‐hydroxyprogest

ISSN:0002-9106    

DOI:10.1002/aja.1001230304

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

年代:1968

数据来源: WILEY

摘要:

AbstractUsing horse radish peroxidase as a tracer for fluid flow, rapid diffusion was demonstrated between sinusoidal lumina and the interhepatocytic spaces of the murine liver. The marker passed rapidly between adjacent sinusoidal cells and filled the space of Disse. Appreciable amounts of peroxidase were also seen in pinocytic and phagocytic vacuoles within sinusoidal cells. Many junctions in the wall of bile canaliculi impeded the passage of the marker, but in some sites this hindrance did not occur. This provides a path for the direct exchange of material between vascular and biliary contents. Such a mechanism may be physiologically controlled. Junctions in bile ductules prevent diffusion of horse radish peroxidase.

ISSN:0002-9106    

DOI:10.1002/aja.1001230305

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

年代:1968

数据来源: WILEY

摘要:

AbstractSpleens from neonatally thymectomized and nonthymectomized young rats were studied histologically and histochemically to elucidate the development of the splenic immune system with and without thymus.In intact animals primitive germinal center activity could be elicited with antigen as early as 13 days of age. More definitive germinal centers lacking tingible body macrophages were observed at 18 days of age. Germinal centers containing tingible body macrophages did not develop until 35 days of age in response to antigenic stimulation. This coincided with maximal development of the marginal zone of medium‐sized lymphocytes and the mature development of nodular macrophages possessing strong acid phosphatase activity.Neonatally thymectomized rats developed marginal zones and germinal centers similar to control littermates when the young animals were maintained on tetracycline. Thymectomized animals not given tetracycline showed disturbances in splenic development. These are discussed.The results suggest that the thymus may be critical to the immune system in rats from birth to about 30 days of age but is not essential to its function beyond this period. Marginal zone lymphocytes and germinal center cells proliferate normally and mature to the plasma cell stage in the absence of a thymus if the animals are maintained on tetracycline beyond this critical ag

ISSN:0002-9106    

DOI:10.1002/aja.1001230306

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

年代:1968

数据来源: WILEY

摘要:

AbstractThymidine‐H3radioautography was used to study the proliferative response to penetrating wounds of the mouse spinal cord. In one group of animals mononuclear leukocytes which infiltrate nervous tissue wounds were labeled by injecting thymidine‐H3prior to injury. In two other experimental groups the cells which synthesized DNA in the nervous tissue following the injury were labeled by giving either a single injection of isotope shortly before sacrifice or by giving four injections during the 24 hours prior to sacrifice. The animals were sacrificed over a five day period following spinal cord injury. Although the labeled nuclei in all three groups were similar in appearance, their distribution about the lesion was very different. The labeled blood cells were greatly concentrated at the wound, while the cells that responded to injury by DNA synthesis were much more evenly spread throughout the tissue. When these distributions were converted to straight lines and compared statistically, there was a very low probability that the group of cells labeled before injury and the two groups labeled after injury were samples from the same population. Although mononuclear leukocytes do proliferate in and around nervous tissue wounds, other cells originally present in the nervous tissue wounds, other cells originally present in the nervous tissue must also prolifer

ISSN:0002-9106    

DOI:10.1002/aja.1001230307

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

年代:1968

数据来源: WILEY

摘要:

AbstractThe newt spleen has an outer region, the red pulp, that consists of reticular fibres, reticular cells, and fixed macrophages forming a framework within which erythropoiesis occurs, and an inner region, the white pulp, consisting of a reticular framework containing predominantly lymphocytes. The fine structure of the following leucocytes, namely lymphoid cells, reticular cells, macrophage, haemocytoblasts, plasma cells and neutrophilic, basophilic and eosinophilic granulocytes is, in general, similar to that of the corresponding mammalian blood cells. However, in contrast, all the nuclei contain large numbers of interchromatin granules and a differentiated region termed the nuclear light‐staining zone because of its electron‐scattering properties. Furthermore the specific granules of the eosinophilic granulocytes are structureless whereas those of the basophilic granulocyte have crystalline regions. The structure and distribution of the granular, fibrillar, tubular and vesicular components of the cytoplasm of each cell type is descri

ISSN:0002-9106    

DOI:10.1002/aja.1001230308

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

年代:1968

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001230301

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

年代:1968

数据来源: WILEY