摘要:

AbstractThe processes involved in the release of secretory products from the parenchymal cells and the movement of these products into the circulating blood were studied by electron microscopic observations on the adenohypophyses of virgin estrous rabbits. The released secretory products were found in the form of discrete granules, with or without a perigranular membrane, in intercellular spaces, between the plasma membrane and the parenchymal basement membrane, in the perivascular space, in the endothelial cytoplasm, and in the lumen of capillaries. Vesicles containing material which resembled that in the perivascular space were observed in endothelial cells.Interpretation of these observations has led to the proposal of the theory that secretory products of the adenohypophysis may be liberated from parenchymal cells in the following way: by fusion of the perigranular membrane with the plasma membrane (merocrine) or by the detachment of small processes containing secretory granules (“microapocrine”). It is further believed that the discharged products may be transported into circulation in three different manners: by diffusion of dissolved material through the fenestrated endothelium, by active transport of dissolved secretory products by the endothelial cells, or by active transport of intact secretory granules through the endothelial cytopl

ISSN:0002-9106    

DOI:10.1002/aja.1001150202

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

年代:1964

数据来源: WILEY

摘要:

AbstractThe hearts of dogs, cats, monkeys and lambs were studied by methylene blue perfusion and/or immersion. The principle types of sensory nerve terminals found in these hearts were end‐nets and complex unencapsulated endings. End‐nets are formed by the anastomoses of the branched dendrites of several apparently different myelinated fibers. Complex unencapsulated endings are discrete much branched endings of medium to large sized fibers and vary greatly in form and size.The epicardium is supplied mainly with complex unencapsulated endings of highly variable form. End‐nets are rare in this location.No sensory endings were demonstrated in the myocardium. Motor terminals in the form of fine unmyelinated nerve fibers were demonstrated on both atrial and ventricular myocardial muscle fibers.The atrial endocardium, particularly in the areas of the openings of the great vessels and on the interatrial septum is the best innervated area of the heart. Endnets, and a wide variety of complex unencapsulated nerve endings occur singly and in combination in these areas.The ventricular endocardium is supplied only with end‐nets.The tricuspid and mitral valve leaflets have both end‐nets and complex unencapsulated endings while the aortic and pulmonary valve leaflets have only end‐nets.The cardiac complex unencapsulated nerve endings (baroreceptors) are morphologically and functionally homologous to complex unencapsulated nerve endings (“stretch” receptors) in other areas of the organism.The detailed structure and function of the end‐net terminals re

ISSN:0002-9106    

DOI:10.1002/aja.1001150203

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

年代:1964

数据来源: WILEY

摘要:

AbstractThree distinct types of gland cells occur in adult human ovaries and those of other mammals. These are: (1) Interstitial gland cells formed from the theca interna cells of degenerating (atretic) follicles, hence present from infancy to old age; (2) Thecal gland cells formed from the theca interna cells of ripening follicles, hence present only in individuals that are sexually mature or nearly so, and in these only at or near the time of ovulation; (3) Luteal cells formed from the granulosa cells of ovulated follicles and from the undifferentiated stroma cells surrounding these, and in certain species also from the same sources in relation to atretic follicles. These latter are the so‐called accessory corpora lutea. Primary and accessory corpora lutea are present normally only after ovulation occurs and appear to function for a relatively short time unless pregnancy ensues. In certain species other types of gland cells occur in the ovary and mesovarium; these include the paraluteal cells of the human ovary. Paraluteal cells are not persistent thecal gland cells, but are differentiated from surrounding stroma after the thecal gland disappears. They are probably intermediate stages in the differentiation of luteal cells from stroma cells. Planimetric measurements and computations made from serial sections of human ovaries indicate that in non‐pregnancy and early pregnancy the volume of interstitial gland tissue is less than 1% of the total ovarian volume. However, in the last trimester of gestation, the relative amount of interstitial gland tissue increases rapidly to roughly from 4% to 6% of the total ovarian volume. The largest amount in our series was 5.6%. Luteal gland tissue at the height of its development in the first trimester of gestation reached 31% of the total ovarian volume. In human ovaries the cells of the interstitial gland tissue of late pregnancy seem to be consistently larger and to have a more finely granular cytoplasm than those of early pregnancy or nonpregnancy. The literature shows that mammalian interstitial gland cells of comparable origin to the human cells discussed in this paper have the following characteristics which are known to be indicative of steroid secretors: Numerous birefringent, acetone soluble, autofluorescent granules which react with sulphuric acid and are Schultz and Schiff positive; mitochondria with anastomosing tubular cristae; and smooth tubular endoplasmic reticulum. Physiological studies so far reported have indicated possible estrogen, androgen, and progesterone production by interstitial gland cells, but all of the evidence is too scanty, indirect, and at times contradictory to be convincing. Since interstitial gland cells are present from birth to old age, and show cycles of abundance and differentiation correlated with the reproductive age and cycles, they may prove to be the most important ovarian gland cells when their function is fully underst

ISSN:0002-9106    

DOI:10.1002/aja.1001150204

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

年代:1964

数据来源: WILEY

摘要:

AbstractThe functional pronephros in early larvae ofAmbystoma opacum, studied in serial sections, consists of an anterior and posterior nephrostome, respective proximal tubules which fuse into a common proximal tubule, a ciliated intermediate segment, and a distal tubule, which leaves the pronephros posteriorly as the nephric duct. In the coelom medial to each pronephros is a glomus, arising from the dorsal aorta.In electron micrographs of osmium‐fixed, methacrylate‐embedded pronephros and glomus, the fine structure generally resembles that seen in adult kidneys. Proximal tubule cells show a brush border of irregular microvilli, tubular invaginations, resorption granules, and very few basal infoldings. Cells of the distal tubule have numerous radially‐oriented mitochondria, and the basal infoldings are generally well developed. The fine structure of the nephric duct seems to resemble that of the distal tubule. Cells of the nephrostomes and intermediate segment bear cilia of usual fine structure, and contain melanin granules, lipid droplets and slender mitochondria. The glomus resembles a glomerulus in having an endothelium with sparse pores, a basement membrane, and epithelial cells with numerous interdigitating foot processes.The similarity at the fine structure level between the pronephros and the more posterior mesonephros and metanephros of adult vertebrates suggests the serial homology of vertebrate nephrons, and thus constitutes further evidence for the archinephros or holonephros theory of the origin of vertebrate ki

ISSN:0002-9106    

DOI:10.1002/aja.1001150205

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

年代:1964

数据来源: WILEY

摘要:

AbstractThe submaxillary glands of the adult desert rat, antelope squirrel, rat, mouse and hamster have in common low levels of amylolytic enzyme in comparison with the relatively high levels of parotid gland amylase in these rodents. Submaxillary gland acini are classed as seromucous secreting although there is some variation in the carbohydrate histochemistry of these secreting units. Granular tubules are absent in antelope squirrel submaxillary glands and they are present in the submaxillary glands of the desert rat, rat, mouse and hamster. Electron micrographs reveal the presence of numerous basal folds in the acini of antelope squirrel submaxillary and parotid glands. These structures were not observed in the salivary gland acini of the hamster. Golgi membranes and “immature” secretion granules are topographically intimate in parotid glands of the hamster and antelope squirrel. In the submaxillary glands of these two rodents, the secretory material appears to originate in relation to the endoplasmic reticulum and secondarily, the granules become associated with a diffusely arranged system of Golgi membranes. The sublingual glands of all the rodents of this study are predominantly ones that produce mucous secretion and contain well developed striated duct systems. Of the salivary glands investigated in this study, the parotid glands of the rat, mouse and desert rat produce an isotonic saliva; the saliva of the other glands is definitely hypoto

ISSN:0002-9106    

DOI:10.1002/aja.1001150206

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

年代:1964

数据来源: WILEY

摘要:

AbstractThe trophoblastic cells of the basal plate at the end of pregnancy still have an important hormonal function, in contrast to the decidual cells which appear to exert their main function at the onset of pregnancy. Possibly the decidual cells are functionally replaced by the basal trophoblastic cells, which phagocytize and destroy them. Although both types of cells are structurally quite similar and appear to produce the same hormones, but at different times, genetically they are very different. They degenerate morphologically in much the same way, but the cause for the retrogressive change for each is distinct. The trophoblastic cells degenerate with reticulum‐fibrinoid inclusions which they have mainly phagocytized. The decidual cells perish with collagen inclusions formed from collagen fibers they in turn produce

ISSN:0002-9106    

DOI:10.1002/aja.1001150207

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

年代:1964

数据来源: WILEY

摘要:

AbstractA study of the placenta of the spotted hyena (Crocuta crocutaErxleben), based on five specimens from early in the second third of pregnancy to full term, is presented. Resembling the dog and cat in the retention to term of a large allantois and a medium‐sized yolk sac, the hyena is unique among Carnivora in the possession of a hemochorial villous placenta, allied structurally more to that of New World monkeys than to the other carnivores. The intimacy of the fetal and maternal circulations is further increased by so‐called intraepithelial capillaries in the syncytial trophoblast. The hyena, unlike most carnivores, possesses no central hematoma or marginal deposit of pigment, and lacks specialized structures in the chorionic membrane. The cytotrophoblast, however, does undergo modifications associated with phagocytosis of histotrophe in the paraplacental regions and in the junctional zone of the placenta proper.The principal mode of entry of maternal blood is directly into the subchorial sinus, into which uterine arteries, carried up in a crescent of gestational endometrial tissue at the margin of the placenta, empty. Smaller arteries reach the subchorial sinus in maternal septa that traverse the entire trophoblastic zone. Major arteries do not discharge blood at the base of the placenta, but basal drainage constitutes the sole means of return of blood to the uterine veins. The phylogenetic significance of the morphogenesis and vasculature of the placenta ofCrocutais discus

ISSN:0002-9106    

DOI:10.1002/aja.1001150208

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

年代:1964

数据来源: WILEY

摘要:

AbstractEnzymes involved in oxidative metabolism as well as acid phosphatase were studied histochemically in osteoclasts from newborn normal rats and their littermates who suffered from a generalized defect in bone resorption (the “ia” rat). The osteoclasts of normal rats demonstrated intense activity for DPNH and TPNH diaphorase as well as succinic, malic and lactic dehydrogenase. Isocitric and glutamic dehydrogenase were less than one‐half as active but no less definite. In the “ia” rat the reaction for the diaphorases and dehydrogenases were exactly as observed in the normal. Acid phosphatase was observed in normal osteoclasts as a general cytoplasmic reaction and also in a band of concentrated activity at the junction of the cell and bone. The osteoclasts from “ia” animals had greater acid phosphatase activity (more than twice as reactive) than the normal. However, the “junctional band” was only rarely observed in this anomaly. The junctional band may represent sites into which enzymes such as acid phosphatase are secreted in the resorption process and therefore only associated with active osteoclasts. It is possible that the “ia” rat may successfully form but n

ISSN:0002-9106    

DOI:10.1002/aja.1001150209

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

年代:1964

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001150201

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

年代:1964

数据来源: WILEY