摘要:

AbstractBaboon placentae were studied which ranged in age from 13 to 40 days. Implantation in the baboon is superficial and a single, discoid, villous hemochorial placenta is formed. No chorionic villi develop peripheral to the placenta and there is no decidua capsularis. Trophoblastic tissue within the placenta is of two types, cyto‐ and syncytiotrophoblast. The chorionic villi are short and straight at 13 days but have begun to branch by 16 days. The villi consist of a mesenchymal core surrounded by a single layer of cytotrophoblast which is in turn surrounded by a layer of syncytiotrophoblast. Cytotrophoblastic cells from the distal tips of the villi spread over the maternal surface of the placenta and form a complete cytotrophoblastic shell against the uterine stroma. Maternal blood enters and leaves the intervillous space through clefts in the cytotrophoblastic shell which connect with arteries and expanded venules within the endometrium. A limited decidualization of the uterine stroma takes plac

ISSN:0002-9106    

DOI:10.1002/aja.1001260102

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

年代:1969

数据来源: WILEY

摘要:

AbstractBaboon placentae ranging in age from 45 to 175 days were studied for progressive changes in their morphology. The baboon embryo implants superficially and develops a single, discoid, villous hemochorial placenta. The remainder of the chorion is membranous and a true decidua capsularis is not formed. A lobular structure is developed during the fetal period. At 45 days the amnion only partially fills the chorionic cavity but by 60 days has expanded and the two membranes are directly contiguous. Trophoblastic tissue is of two types: cytotrophoblast and syncytiotrophoblast. Cytotrophoblast is found primarily in the chorionic plate and cytotrophoblastic shell. The chorionic villi are originally composed of a double layer of trophoblast; cytotrophoblast internally and syncytiotrophoblast externally. The cellular layer gradually disappears so that by full‐term the villous walls are formed by a single layer of syncytiotrophoblast. Hofbauer cells are common within the villous cores, diminishing in number toward term. Large amounts of collagenous connective tissue develop in the chorionic plate and in the villi, and fibrin and fibrinoid materials accumulate in the basal plate and anchoring villi. The endometrium is decidualized to its greatest extent by the beginning of the fetal period and undergoes only minor cytological alteration throughout the remainder of gestatio

ISSN:0002-9106    

DOI:10.1002/aja.1001260103

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe availability of a perfectly preserved lung from a premature infant of 30–32 weeks that lived nineteen and a quarter hours has made possible the first wax reconstructions of the terminal air spaces in the canalicular period of fetal growth. Here, as in the newborn, the most distal respiratory bronchioles give rise to two pairs of clusters of saccules, but with this difference: each saccule (lined by flat epithelium) is separated from others by a spongy, vascular, connective tissue matrix. By reconstructing just the cavities of the saccules one can study the bizarre shapes presented by the saccules. In pattern the latter closely resemble peripheral alveolar saccules of the child lung modelled by the writer. Seemingly, therefore, this fetal period is the one in which the terminal generations of branches are being elongated and their shapes determined by invading capillaries and connective tissues. Clinically, one may conclude that peripheral diffusion of gases (in the infant or adult lung) does not follow any such simple dichotomous pattern of flow as has been hitherto assume

ISSN:0002-9106    

DOI:10.1002/aja.1001260104

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

年代:1969

数据来源: WILEY

摘要:

AbstractSkin of the back, belly, dewlap and parietal eye were studied as illustrations of the principal variations of chromatophore arrangement and color range present inAnolis carolinensis. The fine structure of the chromatophores, disposed in sharply stratified layers, was investigated. The most superficial chromatophore layer consists of xanthophores, which impart a greenish‐yellow color to the skin. These cells are filled with two types of membrane‐bounded inclusions containing pteridines and carotenoids, respectively. Basal to the xanthophores is a 2–4 cell‐deep layer of iridophores. These cells are filled with undulating layers of birefringent rodlets, presumably guanine, arranged parallel to the skin surface. The most basal chromatophores are large melanophores, positioned above a thick collagenous basement lamella. Migration of melanin granules into the dendritic processes, which terminate at the dermoepidermal junction, cause the lizard to change from green to brown. The back skin, which ranges in color from bright green to brown, contains the full complement of dermal chromatophores. The xanthophore region is much reduced in the cream‐colored belly. The dewlap, which is bright red when extended, bears a thick layer of iridophores through which are scattered melanophores, and erythrophores containing red pigment. The dermis over the parietal eye contains only xanthophores and a basemen

ISSN:0002-9106    

DOI:10.1002/aja.1001260105

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

年代:1969

数据来源: WILEY

摘要:

AbstractTo analyze the behavior of spermatogonia in the monkey, the cytological features, topographical arrangement and frequency of the two classes of type A (A1, A2) and the four classes of type B (B1–B4) spermatogonia were determined in dissected tubules, fixed in Carnoy, stained with hematoxylin and mounted “in toto.” The capacity of spermatogonia to divide was also analyzed in radioautographed testicular sections from an animal injected with tritiated thymidine.The type A1spermatogonia, characterized by nuclei containing deeply stained, finely granulated chromatin, were found to be non‐dividing elements. The type A2spermatogonia, characterized by nuclei showing palely stained, coarsely granular chromatin, all divided in stages IX–X of the cycle of the seminiferous epithelium to yield equal numbers of new type A2cells and type B1spermatogonia. The type B1, as the other type B cells, were characterized by nuclei containing granules or flakes of deeply stained chromatin. While the type A2spermatogonia remained dormant until stage IX of the following cycle, the type B1cells all divided during stage XII to yield twice their number of type B2spermatogonia. These, in stage II, divided to give twice as many type B3, which, in stage IV, divided to produce twice as many type B4spermatogonia. Lastly, in stage VI, the latter elements all divided to yield spermatocytes.Thus, the type A1spermatogonia, did not appear to be actively involved in the production of spermatocytes and were tentatively considered as “reserve stem cells;” the type A2spermatogonia, were identified as “renew

ISSN:0002-9106    

DOI:10.1002/aja.1001260106

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

年代:1969

数据来源: WILEY

摘要:

AbstractTwenty‐seven mature female macaques were ovariectomized at various times during the menstrual cycle. The ovaries were sectioned serially and each vesicular follicle was measured and classified according to size and developmental state. Also noted was the presence of differentiated and undifferentiated glandular tissue.The data showed that when the corpus luteum was active the largest follicle in each animal was not less than 1 mm in diameter, and that when the corpus luteum began to degenerate follicular enlargement commenced. Most follicles became atretic when under 1 mm in diameter, except for a few in the late follicular stage. The maximal diameter for an atretic follicle was 3.1 mm and for a developing follicle 6.3 mm.Interstitial gland tissue (theca interna of atretic follicles) was noted in large amounts just before ovulation while minimal amounts were present throughout the rest of the cycle.Other glandular types occasionally seen were aberrant and accessory corpora lutea, cords of cells in the stroma and adrenal rest

ISSN:0002-9106    

DOI:10.1002/aja.1001260107

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe distribution of cholinergic and adrenergic nerves in the cat ureter was studied by specific histochemical techniques for acetylcholinesterase and norepinephrine. The innervation of the ureter is characterized by (1) a generalized dual cholinergic and adrenergic nerve supply, (2) the presence of muscular innervation, (3) a continuity of terminal muscular and vascular nerves, (4) a widespread distribution of ganglion cells except in the pelviureteric area and (5) regional variations in the density of both cholinergic and adrenergic elements.On the basis of these findings, it is suggested that in the cat ureter peristalsis has a myogenic origin in the proximal end of the ureter, but its distalward propagation along the abdominal and pelvic segments is controlled by a dual sympathetic and parasympathetic influence which is mediated in part through a system of intrinsic ureteric ganglion cells.

ISSN:0002-9106    

DOI:10.1002/aja.1001260108

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

年代:1969

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001260101

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

年代:1969

数据来源: WILEY