摘要:

AbstractKeratinization or mucification of the epithelium of the rat vagina is related to the hormonal state of the animal. During the normal cycle and after the administration of exogenous hormones (estrogen and progestin) to spayed animals, the surface characteristics and topography of the vaginal epithelium were studied with the scanning electron microscope. During estrus and under the influence of estrogen, the superficial cells were keratinized, overlap each other like shingles, and are continuously sloughed off. Like the surface of other keratinizing epithelia, theirs has a characteristic microridge pattern. In ovariectomized animals, the apical surface is covered with microvilli instead of microridges, and the cells resemble hexagonally shaped units, tightly bound instead of overlapping each other. At the boundary between the cells, a ridge demarcates the cells. The surface configurations of progestin‐treated, progestin plus estrogen‐treated, and diestrous animals are the same as in spayed anim

ISSN:0003-276X    

DOI:10.1002/ar.1091780302

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

年代:1974

数据来源: WILEY

摘要:

AbstractChronic hyperthyroidism was induced in radiothyroidectomized adult albino rats by feeding a diet of 0.3–0.4% desiccated thyroid for four to ten weeks. The left ventricle from control and hyperthyroid animals was examined with the electron microscope after perfusion fixation with 3% phosphate buffered glutaraldehyde and postfixation in 1% osmium tetroxide. No differences were discerned in the appearance of the Golgi zone, glycogen, lipid, lysosomes, sarcoplasmic reticulum, or the sarcomere ultrastructure of the ventricle from hyperthyroid animals compared with untreated animals. Changes were noted in the mitochondria. These included marked hypertrophy without increase in numbers and localized areas of vacuolization and disorientation of the cristae. Apparently these changes are reversible since the ventricular mitochondria of previously hyperthyroid animals allowed to return to a euthyroid state were indistinguishable from those seen in the control grou

ISSN:0003-276X    

DOI:10.1002/ar.1091780303

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

年代:1974

数据来源: WILEY

摘要:

AbstractLeydig cells appear in the hamster testis between 12 and 13 days gestation. The cells are round to oval, with prominent lipid droplets, abundant smooth endoplasmic reticulum, large mitochondria with tubular cristae and well developed Golgi complexes. Cells of this type are found in pairs and groups around interstitial blood vessels during the last three days of gestation and up to the fourth day after birth, when regressive changes begin to appear. During the second postnatal week, most cells in the interstitial regions are undifferentiated, with only a few scattered partially differentiated Leydig cells remaining. The time during which fully differentiated Leydig cells are present encompasses the period of sexual differentiation of the reproductive ducts and the critical period for differentiation of sexual behavior.

ISSN:0003-276X    

DOI:10.1002/ar.1091780304

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe endocrine pancreas of the Coturnix quail consists of two major islet configurations. Islets containing B and D cells are found in all four lobes of the pancreas, but islets consisting of A and D cells occur with regularity only in the third and splenic lobes. Pancreatic islets comprise only a small percentage of the tissue volume in the ventral, dorsal and third lobes. In the splenic lobe, however, one or more A islets surrounded by numerous small B islets may constitute more than 50% of the total cellular mass.Secretory granules of the B cells are aldehyde fuchsin‐positive and show three distinct profiles at the ultrastructural level. The PTAH‐positive A granules are usually round or teardrop shaped and are of uniform electron density. D cells are argyrophilic; their secretory granules are of heterogeneous densities. These cells are located at the peripheries of the B islets, but are freely dispersed in the A islets. At the electron microscopic level, Type IV cells, previously not reported in avian islets, are found mainly in the A islets of this species. This unusual cell type contains granules of differing densities, but, unlike those of the D cell, they are often rod‐shaped and biconcave in profile.Because of the distinct segregation of islet types, and the peculiar arrangement of the D and Type IV cells within the two kinds of islets, it is suggested that the Japanese quail may serve as a model for investigations of avian islet fun

ISSN:0003-276X    

DOI:10.1002/ar.1091780305

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe forebrain of the isolated central nervous system of frogs was fixed by freeze substitution and studied with the electron microscope. The extracellular space (ECS) of brains kept for 15–20 min in a physiological salt solution at room temperature varied from an appreciable to a negligible one. In electron micrographs exhibiting a large ECS the tissue elements had a uniform electron density. The EMs with little space featured in some instances a moderate swelling of presynaptic terminals and other tissue elements. Brains kept in a cooled medium or a salt solution with MgCl2added exhibited invariably an abundant ECS. Treating the brain with a 100 mM KCl solution 5–90 sec before freezing yielded EMs with a contracted ECS and swollen tissue elements, many of which could be identified as dendritic spines. This effect of KCl was in many experiments prevented by bathing the brain in a salt solution containing 10 mM MgCl2or in a Ca‐free sol

ISSN:0003-276X    

DOI:10.1002/ar.1091780306

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe intercalated discs of the myocardium from the active and hibernating bat hearts were investigated by means of electron microscopy and use of lanthanum and horseradish peroxidase as tracers. The discs are composed of four zones: intermediate junctions, desmosomes, nexuses, and undifferentiated areas. Of particular interest are the two different types of nexuses. Nexus I without lanthanum displays a 150 Å overall width and an apparent 80 Å intercellular space, ranges from 0.5 to 4.0 μ in length, and is seen in the longitudinal segments of the intercalated disc. With application of lanthanum, however, nexus I shows that the tracer has penetrated a 20 Å gap junction and resembles nexus II. Nexus II with and without lanthanum has a 200 Å overall width and a gap junction of about 20 Å, is generally less than 0.3 μ in length, and is found on the transverse or oblique segment of the intercalated disc. Both nexuses I and II seem to block the passage of peroxidase. The plasma membranes of nexus I may have a different molecular organization from those in nexus II as reflected by their contrasting response to fixation and/or staining. Combinations of the various junctions show that the zones of adhesions (intermediate junctions and desmosomes) are adjacent to the regions of possible lowered resistance (nexus I and II). These findings suggest that adhesion sites insure the proper connection and functioning of the nexuses and support the electrical observations that the heart forms a “physiological sy

ISSN:0003-276X    

DOI:10.1002/ar.1091780307

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe influence of different estrogen‐progesterone ratios on DNA synthesis in the rat uterus was investigated. Ovariectomized rats were injected subcutaneously daily for three days with either oil, 1 μg estradiol‐17β dipropionate or estradiol and 1, 5, 10 or 15 mg progesterone. Tritiated thymidine was administered one hour prior to necropsy. Thymidine indices were determine for both the luminal and glandular uterine epithelia while the total number of labeled nuclei in the stroma was ascertained. In all tissues studied, significantly more nuclei from uteri of rats given only estrogen replicated DNA than from those of the oil‐treated controls. While concurrent treatment with estradiol and 1 or 15 mg progesterone did not statistically alter the extent of thymidine incorporation in the luminal epithelium and stroma from that observed following estrogen alone, 5 or 10 mg progesterone given with estrogen significantly suppressed the labeling activity in the luminal epithelium and stroma from that of the estrogen‐treated rats. However, the thymidine indices of the glandular epithelium from uteri of rats injected with all combinations of both hormones were significantly lower than that from uteri of estrogen‐treated rats. These data indicate that the estrogen–progesterone ratio is important in regulating cell turnover in the luminal epithelium and stroma of the rat uterus but not in glandul

ISSN:0003-276X    

DOI:10.1002/ar.1091780308

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

年代:1974

数据来源: WILEY

摘要:

AbstractIt has often been reported that facial proportions remain constant throughout the fetal period. Such conclusions, however, have been based largely on the erroneous assumption that two dimensions are growing isometrically if one bears a statistically significant linear relation to the the other. In order to test the hypothesis that proportion is independent of time, sagittal histologic sections from 32 human fetuses (12–25 weeks) were analyzed cephalometrically. The linear regression on head length (HL) and the associated coefficient of correlation were calculated for each of a variety of craniofacial measures. In addition, all linear dimensions were transformed so that the size of the anterior cranial base was held constant throughout the series. It was assumed that if shape be constant, all Y‐intercepts should be zero, and angular and transformed linear dimensions should show no statistically significant linear correlation with HL. These three criteria were met uniformly by facial and anterior cranial base dimensions, but not by measurements which involved the posterior cranial base. It is concluded, therefore, that in the sagittal plane the second trimester mandible, midface, and anterior cranial base grow isometrically, while the posterior cranial base becomes relatively smal

ISSN:0003-276X    

DOI:10.1002/ar.1091780309

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe patterns of the superficial veins of the cubital region were studied in 536 Indian subjects both living and dead. Three basic pattern types were noted. Type I had a median cubital vein joining the cephalic and basilic veins in the cubital region. Type II had the cephalic vein itself draining into the basilic vein in the cubital region. Type III showed the absence of a direct communication between the cephalic and basilic veins in the cubital region. The median vein of the forearm in these latter cases joined either of the cephalic and the basilic veins (type III A) or after bifurcating into a median cephalic and a median basilic vein joined both these veins (type III B). Type I was found to be the most common pattern (67.5%) followed by type II (19.5%), with types III A and III B accounting for 6% and 6.5% of the cases, respectively. Renaming of the median cubital vein as the oblique cubital vein because of its direction and renaming of the median basilic and lateral basilic veins as medial and lateral cubital veins since they follow the medial and lateral borders of cubital fossa respectively has been suggested.

ISSN:0003-276X    

DOI:10.1002/ar.1091780310

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

年代:1974

数据来源: WILEY

摘要:

AbstractMacroscopic and microscopic examination of adipose tissue was carried out in a series of 20 human fetuses, ranging in weight from 380–3032 gm, in an attempt to identify all areas of brown (multilocular) fat development and growth. Brown fat distribution in the human fetus takes the form of a highcollared vest affording coverage to the cervical, thoracic and abdominal viscera. Much of this fat lies deep within the body immediately outside the pleural and peritoneal membranes. the remainder overlies or borders muscles of the shoulder girdle and neck as distinct brown fat deposits deep to the subcutaneous layer of white (unilocular) fat. All brown fat bodies contain unilocular cells but they occur in very small numbers in the brown fat bodies of the posterior cervical triangle, anterior mediastinum and perirenal and suprailiac regions. Brown fat bodies usually develop along the course of large blood vessels and several of them develop direct vascular connections with the liver and kidneys. The total weight of fetal brown fat increases at a rate directly proportional to that of the liver and kidneys up to 2134 gm body weight and to that of the liver beyond this weigh

ISSN:0003-276X    

DOI:10.1002/ar.1091780311

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

年代:1974

数据来源: WILEY