ISSN:0003-276X    

DOI:10.1002/ar.1091820102

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

年代:1975

数据来源: WILEY

摘要:

AbstractFrog retinae, fixed only in buffered glutaraldehyde, were embedded for sectioning in glutaraldehyde polymerized with urea. In suitably thin sections globular substructures were seen in negative contrast after ionic staining with uranyl acetate and lead citrate, or after staining with neutralized phosphotungstic acid. Efforts to extract at least some of the lipid from sections before ionic staining enhanced the visualization of the “globules.” Exposure to KMnO4solution, used as an oxidative section stain, also outlined globular substructure in negative contrast, but with the additional feature that positively stained surface “leaflets” associated with the aqueous compartment were well defined. Staining sections with OsO4vapor resulted in positively stained membranes, but without any evident substructure. However, when sections which previously had been exposed to OsO4vapor were secondarily stained with uranyl acetate and/or lead citrate, positively stained globular substructures then were revealed.The globular substructures always were centered in the hydrophobic core region of the disc membranes, and symmetrically spanned the full thickness of this layer. The diameter of individual particles approximated 50–55 Å. Reasons are presented for the supposition that the evident globules incorporate at least hydrophobic components of rhodopsin molecules. Findings are discussed in relation to various models of disc membrane organization that have been proposed in re

ISSN:0003-276X    

DOI:10.1002/ar.1091820103

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe development of the granular convoluted duct in the submandibular gland of male rats, 4 to 12 weeks of age, was investigated. During this period, the average weight of the gland increased from 213 to 526 mg, the total DNA and RNA contents doubled, and the protein content tripled. Radioautographs were prepared from Epon embedded sections of the gland of the rats given3H‐thymidine and stained with toluidine blue. The glands of 4‐week‐old rats consisted mainly of acinar cells (45%), intercalated ductal cells (20%) and striated ductal cells (16%). A few granular convoluted ductal cells were seen in the striated duct close to the intercalated duct. The frequency (and absolute number) of granular convoluted ductal cells increased linearly from 1% (3 × 106) at four weeks to 26% (68 × 106) at eight weeks, while the calculated number of striated ductal cells remained stationary. The absolute number of acinar cells and intercalated ductal cells nearly doubled between four to eight weeks of age. The proliferative activity of all cell types declined with age but between six and ten weeks of age the rate of proliferation of ductal cells was relatively higher than the rate of proliferation of the acinar cells. Morphologically the size and number of granules in the granular convoluted ductal cells increased with age. Based on the above data it is concluded that the granular convoluted ductal cells developed from that segment of the striated ductal cells which is in close proximity with the intercalated ductal cells. The heterogeneity of the granules in the granular convoluted ductal cells observed from six weeks of age might denote the functional diversity of th

ISSN:0003-276X    

DOI:10.1002/ar.1091820104

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

年代:1975

数据来源: WILEY

摘要:

AbstractSmooth muscle cells were demonstrated adjacent to the aqueous outflow pathway in rabbit eyes. The cells were arranged as a discontinuous band, one to three layers thick and extended from the termination of Descemet's membrane to the ciliary body. Most of the cells were oriented with their long axes at right angles to the aqueous plexus, but many were arranged in a direction parallel to the plexus. The organization of the cells suggests that their contraction would exert a bi‐directional force, and therefore, affect aqueous outflow resistanc

ISSN:0003-276X    

DOI:10.1002/ar.1091820105

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe mitochondrial population of sustentacular cells in the testis of the amphibian,Xenopus laevis, has been examined by electron microscopy. Three distinct types of mitochondria have been observed. The first and most common mitochondrial type is a “typical” organelle with a rod‐like profile containing tubular to plate‐like cristae. The second mitochondrial form is characterized externally by irregular bulbous protrusions and internally by increased numbers of tubular cristae. The third mitochondrial type, which is usually ovoid in profile, has the most unusual internal membrane configuration, consisting of pleated folds pierced by regular rows of fenestrations. Mitochondrial type one is found in all sustentacular stages, mitochondrial type two first appears in sustentacular cells surrounding early spermatids, and mitochondrial type three is observed only in sustentacular cells surrounding spermatozoa. These observations indicate that discrete subclasses of mitochondria are present in sustentacular cells of

ISSN:0003-276X    

DOI:10.1002/ar.1091820106

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe diameters of the ovarian, uterine, and femoral veins and the inferior vena cava were measured during stages of the estrous cycle in intact and hysterectomized mice and at intervals during pregnancy in mice with embryos in both uterine horns or in only the left horn. At metestrus I vein sizes were the least and were not significantly different in intact and hysterectomized mice. Ovarian and uterine veins showed the same or increased diameters at other stages of the cycle; veins enlarged progressively during pregnancy in intact mice. Non‐gravid uterine horns showed little size increase as compared to gravid horns. Increases in vein diameter appeared to be correlated with local production of reproductive hormones.Evidence for transuterine migration of embryos was observed in 21 of 53 mice in which one uterine tube had been ligated or one ovary had been remove

ISSN:0003-276X    

DOI:10.1002/ar.1091820107

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

年代:1975

数据来源: WILEY

摘要:

AbstractPellets of progesterone plus 1 % 16α‐hydroxy‐progesterone (16α‐OH), testosterone plus 1 % 16α‐OH, and estradiol‐17β plus 1 % 16α‐OH were implanted in the right uterine fat mass in ovariectomized (O) and ovariectomized‐hysterectomized (OH) mice. Three weeks later they were killed and the diameters of the ovarian, uterine, and femoral veins and the inferior vena cava were measured and averaged. The averages were compared with averages for O and OH mice bearing pellets of glass and of progesterone, testosterone, and estradiol‐17β without 16α‐OH. It is concluded that in castrate mice the size of ovarian and uterine veins is influenced not by the presence or absence of the uterus but by sex steroids, that progesterone usually causes decreases while testosterone and estradiol‐17β cause increases in vein diameter, and that both the presence of the uterus and the administration of 1 % 16α‐OH are associated with partial inhibition of increases in vein size induced by steroids. Uterine hypertrophy and urinary bladder distention resulting from the administration of testosterone and estradiol‐17β were not preven

ISSN:0003-276X    

DOI:10.1002/ar.1091820108

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

年代:1975

数据来源: WILEY

摘要:

AbstractElectron microscopic observations are reported on the intestine of the African lungfish,Protopterus aethiopicus. The lungfish has a spiral valve rather than a true stomach. Segments of mucosa from this area reveal, by transmission microscopy, that most cells have distinct striated borders with parallel microvilli. Fibrils within the core of the microvilli extend deeply into the cytoplasm. Microvilli on the surface of goblet cells are less regularly arranged than those of absorptive cells. Interspersed among the cells with striated borders are cells, similar in cytologic appearance except that they are covered with tufts of kinetocilia. By transmission electron microscopy, abnormal cilia having one complete complement of microtubules plus incomplete sets from other cilia which share some of the peripheral doublets of the complete cilium are enclosed by a single membrane. Cilia are usual in the intestine of many lower forms but ordinarily absent in higher vertebrates. Their functional significance in this primitive fish is unknown.

ISSN:0003-276X    

DOI:10.1002/ar.1091820109

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe ultrastructure of the myoneural junctions in the body wall muscles has been studied inBranchiobdella pentodontaWhit. A single junctional type has been found. Within the terminal axon there are two types of vesicles, which differ in number, size and electron opacity. The junctional gap contains the basement membrane. The post‐junctional membrane displays concave patches on which slender projections arising from the outer lamina of the sarcolemma extend into the junctional gap. These concave patches overlie a cytoplasmic lamina made up of electron dense materia

ISSN:0003-276X    

DOI:10.1002/ar.1091820110

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe ultrastructure of the hepatocyte of the fetal stumptail monkey was examined with the aim of defining a possible model for studies of fetal drug metabolism. Hepatocytes from fetuses of 80 and 160 days gestation, as well as from one animal one week of postnatal age, were examined and compared to human fetal hepatocytes at 12 and 16 weeks gestation. Marked variation was observed in the amount of lipid and the distribution of organelles within the cytoplasm of the hepatocyte in the monkey population. These differences were attributed to genetic variation. Two changes were seen which correlated with developmental age. The amount of hemopoietic tissue decreased and the amount of smooth endoplasmic reticulum increased as the animal matured. The problems of genetic variation and the relative number of hepatocytes at different stages of development were discussed relative to the use of this animal as a model for fetal durg metabolism studies. Attention to both of these problems is considered necessary for the interpretation of biochemical data in future studies.

ISSN:0003-276X    

DOI:10.1002/ar.1091820111

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

年代:1975

数据来源: WILEY