摘要:

The relationship between mammary gland development and adipocyte formation in rat subcutaneous tissue was studied. Tissue samples from newborn rats and young rats were prepared for histological and histochemical analysis. The development of subcutaneous adipocytes in the young rat is associated temporally and spatially with mammary gland development. The growing mammary gland ducts and the blood vessels and nerves that serve the ducts may physically interact with connective tissue cells, resulting in a population of undifferentiated cells. Adipocytes and a wide variety of cell types may be derived from this pool of undifferentiated cells. Histochemical characteristics of cells of immature ends of mammary gland ducts indicated hypoxic conditions. These conditions may have directed a vascularization process that resulted in a network of adipocytes and capillaries around mammary gland ducts. Thus, under normal conditions, adipocyte formation is an integral phase of mammary gland development in the fetal and yount rat.

ISSN:1422-6405    

DOI:10.1159/000145510

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

The fine structure of the perivascular and the other extraganglionic nerve plexuses in the muscularis externa and the mucosa of the guinea-pig stomach was studied in specimens fixed by perfusion and in specimens fixed by immersion after in vitro incubation in 5-hydroxydopamine. In each of the plexuses, over 50% of the nerves contained ten axons or less; terminal profiles were also much more numerous in sections of nerves of this size than in sections of the larger nerves. Five types of axon terminal were identified in the nerves. Terminals containing mainly large dense-cored vesicles were few, but were more numerous in the perivascular than in the other plexuses. Terminals containing small clear vesicles and large dense-cored vesicles approximately 140 nm in diameter were also few and were confined to the plexuses in the muscularis externa. The remaining types of terminal could be clearly differentiated only in specimens incubated in 5-hydroxydopamine. Terminals containing small clear vesicles were present in large numbers in the plexuses in the muscularis externa and the mucosa. Terminals containing small dense-cored vesicles constituted all but a small proportion of those seen in the perivascular plexuses. They were also seen in small numbers in each of the other plexuses. The remaing type of terminal contained small vesicles which were larger than in the other types and which contained halos of electron-dense material. Such terminals were present only in the plexuses in the muscularis externa and were concentrated in nerves located close to the myenteric plexus.

ISSN:1422-6405    

DOI:10.1159/000145511

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

A histological and ultrastructural study as well as an autoradiographic analysis after injection of tritiated 1,25-dihydroxycholecalciferol (1,25-DHCC) were conducted on the distal convoluted tubules of chick embryos. Distal tubules in the embryo were shown to have the same spatial distribution as described for the adult kidney; they presented a convoluted portion located in the vicinity of the central intralobular veins and straight portions irradiating from this region towards the periphery. The epithelium in these tubules was well differentiated; its cells had numerous interdigitating folds in their lateral boundaries which were especially numerous at the basal ends. This device greatly increased the membrane surface available for interchange and was interpreted as an expression of active water and/or mineral transport. Nuclear concentration of radioactivity was found 2 h after injection of tritiated 1,25-DHCC in both the pars convoluta and the pars recta of the distal tubules. This concentration could be blocked by the previous administration of large amounts of nonradioactive 1,25-DHCC. These facts were interpreted as indicating that distal convoluted tubules in the chick embryo are functionally differentiated and contain target cells for 1,25-DHCC.

ISSN:1422-6405    

DOI:10.1159/000145512

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Patterns of superficial veins of the cubital fossa were studied in 300 persons in Nigeria. Five types were observed in this study. The commonest pattern found in Nigerians was the median cubital vein arising from the cephalic vein a little below the level of the elbow (62% in males and 49% in females). To some extent this incidence is comparable with the findings in Americans (70%) and Britishers (53%). However, there is a clear contrast when compared with Japanese (84%) and Indians (16%). The next commonest pattern in Nigerians was the median vein of the forearm dividing into two and joining the basilic and cephalic veins (24–30%). This pattern was also comparable with Americans and Britishers but is in clear contrast to the findings in Indians and Japanese. The incidence of the other patterns was very low in this as well as in all other report

ISSN:1422-6405    

DOI:10.1159/000145513

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Enteroendocrine cells of the gastric antrum have been examined in the gerbil, Meriones unguiculatus. Gastrin-secreting G cells were identified by immunocytochemical methods and by transmission electron microscopy. They were present in the lower and middle third of the pyloric antral glands. G cells were polyhedral in shape and often extended to the gland lumen where they presented a microvillous and pinocytotic surface. These cells were characterized by numerous electron-dense and immunoreactive secretory granules. Enterochromaffin cells were identified by a serotonin-specific formaldehyde-induced fluorescence method, and by electron microscopy which revealed pleomorphic secretory granules of varying electron densities. These cells also had luminal projections and had a shape and distribution essentially similar to those of the G cells. A third endocrine cell type was identified as Dl cell in the pyloric glands. This cell type was recognized by the presence of numerous secretory granules having an electron-dense core and a clear peripheral space, as also by the presence of microfilament bundles, especially in the peri-nuclear region. The functional correlates of these morphological observations are discussed with reference to their secretory product and the manner of its release, especially by the G cells.

ISSN:1422-6405    

DOI:10.1159/000145514

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

There are two reasons why the fibula shows longitudinal motions. During dorsiflexion the push of the wedge-shaped trochlea tali causes an upward fibular motion; on the other hand, during weight bearing the contraction of the leg muscles effects a downward fibular motion. The specific level of the fibula results from these two correlating forces. While the upward fibular migration is a passive compensative movement, the downward fibular migration is an active stabilizing movement.

ISSN:1422-6405    

DOI:10.1159/000145515

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Tibias of 6-day-old white Leghorn chick embryos treated with β-aminopro-pionitrile (β-APN; 0.1 mg/egg/day) for 4 days and injected with 3H-proline or β-tetracycline on the 11th day were analyzed for incorporation of 3H-proline and 3H-tetracycline. The incorporation of 3H-proline was comparable in the controls and β-APN-treated embryos. However, the incorporation of 3H-tetracycline was significantly lower in β-APN-treated embryos. The bone ash contents were also lower in the latter group. Alkaline phosphatase and Ca+2-ATPase were found to be significantly lower in β-APN-treated embryonic bones. There was, however, no difference in the activity of Na+, K+-ATPase. The histochemical examination showed the alkaline phosphatase to be present on osteoblasts and matrix vesicle plasma membranes at the periosteal surface. The chick embryonic liver tissue showed no significant differences in the activities of any of the above enzymes. The results suggest that β-APN-induced inhibition of the bone mineralization may be due to the bone-specific inhibition of alkaline phosphatase and Ca+2-

ISSN:1422-6405    

DOI:10.1159/000145516

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Pregnant Swiss albino mice at different fetal growth periods were exposed to 150 R gamma rays in the presence or absence of 2-mercaptopropionylglycine (MPG), a SH radioprotector. The weights of litters born to these mothers were recorded at different post-partum intervals. There was an initial weight loss at 1 week after birth followed by a second weight loss after 4 weeks in the unprotected control males, whereas females showed continuous gains in weight from initial loss at 1 week. In the MPG-treated groups, the pattern of weight changes remained the same, but the loss was significantly less than in the controls and the second weight loss in the case of males was not obvious.

ISSN:1422-6405    

DOI:10.1159/000145517

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

The development of Leydig cells from the 1st to the 14th year was electron microscopically investigated in specimens of testicles. Leydig cells and their precursor were found in the interstitium. The precursors of the Leydig cells were usually spindle-shaped and contained few organelles and filamentous structures. Leydig cells were usually found in groups. The nucleus was round and eccentric. The most striking feature of Leydig cells was the abundance of smooth endoplasmic reticulum. It was tubular and vacuolar in appearance. Mitochondria possessed cristae of the tubular type and contained occasionally intramitochondrial granules. Glycogen granules and lipid droplets were noted in the cytoplasm. No Reinke crystalloids were found throughout this period. Leydig cells arose from mesenchymal cells via their precursors. Phases of regression of Leydig cells were observed twice, in the 2nd and 3rd years, and from the 9th to the 11 th year. In these periods the above-mentioned Leydig cells were seldom observed and only degenerating cells were noted. After the 13th year the Leydig cells increased in size and in number.

ISSN:1422-6405    

DOI:10.1159/000145518

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

The lungs of 107 birds of 19 different species from seven orders were fixed in situ. The mean volumes of both fixed lungs together ranged from 0.15 to 95.31 cm3. Histological sections of one lung from each bird were analyzed by point counting with a Zeiss integrating eyepiece to determine the volume densities and thence the absolute volumes of the main functional components of the lung. The mean volume density of the exchange tissue was highest in the 11 passeriform species (53.5%) and lowest in the 2 charadriiform species (34.6%); that for all of the 8 non-passeriform species was 42.6%. The possible significance of these variations in relation to the differing oxygen requirements of these groups of birds is discussed. The parabronchi showed minor variations in the degree of development of the interparabronchial septa, atria, interatrial septa, and atrial muscles. The diameter of the parabronchi (including the mantle of exchange tissue) ranged from about 0.34 mm in the passeriform species to about 0.63 mm in Anser anser; the lumen of the parabronchus accounted for about half of this diameter. Body weight and lung volume were strongly correlated (0.995); the allometric function relating lung volume to body weight was 29.5 w0·988

ISSN:1422-6405    

DOI:10.1159/000145519

出版商:S. Karger AG    

年代:1982

数据来源: Karger