摘要:

AbstractThe cellular and subcellular adaptations in the myocardium of spontaneously hypertensive rats (SHR) were compared with those in Kyoto‐Wistar normotensive rats with cardiac hypertrophy induced by constriction of the abdominal aorta (ACR). Hypertensive blood pressure levels were attained at eight weeks of age in SHR and coincided with the surgically‐induced pressure‐overload in ACR at this age. Specimens from the subepicardial and subendocardial regions of the myocardium from glutaraldehyde‐perfused‐fixed hearts of 16‐week‐old animals were compared.Spontaneous hypertension and aortic constriction are associated with significant and comparable increases in heart rate, blood pressure, heart weight, and left ventricular muscle fiber diameter. While the cardiomegaly in both models was accompanied by a decrease in capillary density, the decrement was greater in the aortic‐constricted rats. Stereological analysis of cardiocytes revealed an increase in myofibril/cell‐volume, and a decrease in mitochondria/myofibril‐volume ratios in both models of cardiomegaly. In addition, double intercalated discs and subsarcolemmal foci containing abundant sarcoplasm with numerous small mitochondria, free filaments and Golgi complexes were commonly observed in both experimental groups. Cell diameter increased by a larger increment in the subendocardium than in the subepicardium, but capillary density was similar in these two regions. While aortic constriction was associated with dilatation of T‐tubules and the non‐specialized junctions of the intercalated disc, the myocardial ultrastructure of SHR was characterized by a greater number of lipid droplets and an increased folding of the intercalated discs comprising the subendocardial region.These findings suggest that data based on surgically‐induced pressure‐overload should be extrapolated cautiously to cardiomegaly associated with spontaneous hypertension. The differences between the adaptations in the two models may be due to either (1) the rate at which hypertrophy occurs or (2) some other, possibly gen

ISSN:0002-9106    

DOI:10.1002/aja.1001520202

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

年代:1978

数据来源: WILEY

摘要:

AbstractA correlated study using freeze‐fracture replicas and routine thin sectioning was done on the ameloblasts which secrete inner enamel in the rat incisor. These ameloblasts are columnar cells aligned in rows parallel to the cross‐sectional plane of the incisor. Each cell has a Tomes' process at its distal end which is contained within a cavity of interrod enamel. Tomes' processes of a particular row of cells are inclined towards the mesial side of the tooth, while those of the next row are inclined towards the lateral side, so that the processes cross each other at 90°. Freeze‐fracture replicas were used to examine the surfaces of ameloblasts between adjacent rows and the surfaces of the cells within the row. Replicas of the surfaces between rows showed that ameloblasts are curved so that their proximal and distal ends (Tomes' processes) are both directed towards the same side of the tooth. The surface of each row bears the impression left upon it by the cells in the adjacent row which have been fractured away. This cell‐impression is also curved, but in the opposite direction to the cells which it crosses. It was thus shown that not only the Tomes' processes of adjacent rows but the entire cell bodies cross one another. This crossing is slight at the proximal ends of the cells, but marked at the level of the distal junctional complex. At this level a cell from a particular row curves across several cells of the neighbouring row and forms large tight junctions with at least two cells in that row. The proximal and distal junctional complexes form zones of tight junctions around the cell. The distal complex is more extensive than the proximal and the tight junctions are better developed between adjacent rows. Gap junctions are, however, larger between cells within the rows. The study demonstrated the effectiveness of freeze‐fracture replicas in obtaining 3‐dimensional details about ameloblast shape, and this information was used to evaluate the supposed movement of ameloblasts during inner enam

ISSN:0002-9106    

DOI:10.1002/aja.1001520203

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

年代:1978

数据来源: WILEY

摘要:

AbstractEleven‐day mouse embryos were cultured in a medium containing cytochalasin B (10 μg/ml) to examine the effect of the drug on the developing CNS. The embryos were exposed to the drug for two hours. After culturing, the embryos were prepared for light and electron microscopy and the neuroepithelium of the cerebral vesicles was examined. The following abnormalities were noted in the cytochalasin B‐treated embryos: (1) mitotic figures were situated in the middle of the neuroepithelial layer instead of on the lumen, indicating that premitotic nuclear migration had been prevented; (2) binucleate cells were found in the neuroepithelial layer, indicating that cytochalasin B does not interfere with mitosis but prevents cytokinesis; (3) the microfilaments usually seen in the apex of the neuroepithelial cells were disrupted and formed an amorphous mass of filamentous material; (4) some neuroepithelial cells were free in the lumen, whereas others protruded into the ventricle but appeared to remain attached to the internal limiting border by their junctional complexes; and (5) in some regions the neuroepithelial cells had broken away from their end‐feet at the basal lamina. These morphological changes were associated with a change in the internal limiting boundary from concave to convex and vacuolation of the external processes of the cells. The relationship between cytochalasin B, microfilaments and these morphological changes is dis

ISSN:0002-9106    

DOI:10.1002/aja.1001520204

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

年代:1978

数据来源: WILEY

摘要:

AbstractYoung male rats received a single intravenous injection of3H‐fucose and were killed after various time‐intervals. Light‐ and electron‐microscopic radioautographic studies of the thymus in animals killed shortly after injection showed that all of the different cell types present incorporated3H‐fucose label. The heaviest uptake occurred in macrophages and in hypertrophic epithelial cells located near the cortico‐medullary border. Somewhat lighter incorporation was observed in medullary and cortical stellate epithelial cells and in cells designated as special cells, while the lightest reaction appeared over lymphocytes.In all cells the label was localized initially to the Golgi apparatus, where, presumably, it was incorporated into glycoproteins. With time, some of the labeled putative glycoproteins in all cell types migrated to the plasma membrane. In macrophages, much of the label migrated to lysosomal bodies, while in the special cells the label migrated to dense bodies which may also be of lysosomal nature. In stellate and hypertrophic epithelial cells much of the label migrated to characteristic vacuoles. The possible relationship between the observed glycoprotein synthesis in these cells and hormone production i

ISSN:0002-9106    

DOI:10.1002/aja.1001520205

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

年代:1978

数据来源: WILEY

摘要:

AbstractAn argyrophilic fourth cell type in the rat pancreatic islet can be differentiated from other silver‐staining cells by using a modification of the Grimelius aqueous silver nitrate technique. Restaining of the tissues using fluorescent techniques with anti‐HPP (Human Pancreatic Polypeptide) serum results in bright fluorescence in the fourth cell t

ISSN:0002-9106    

DOI:10.1002/aja.1001520206

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

年代:1978

数据来源: WILEY

摘要:

AbstractThyroglobulin (TG) was localized in the endostyle of the anadromous sea lamprey,PetromyzonmarinusL. by means of the unlabeled antibody peroxidase‐antiperoxidase immunocytochemical method. TG was found localized on the apical surface and within the cytoplasm of type 2c and 3 cells and in some type 5 cells. By identifying the cells of the endostyle immunocytochemically it may be possible to study more readily the events of endostylar transformation during metamorphosi

ISSN:0002-9106    

DOI:10.1002/aja.1001520207

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

年代:1978

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001520201

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

年代:1978

数据来源: WILEY