Abstract
The capillaries in five human chromophobe adenomas were studied by thinsection and freeze-fracture techniques. Fenestrae were found in the attenuated portions of the endothelium, and plasmalemmal vesicles in the nonfenestrated portions. In freeze-fracture replicas, the fenestrae, 600–700 A in diameter, were revealed as circular holes in fracture face A and circular broken-off necks in face B, some 40–60 occurred per μm2. When the fracture process passed in a stepwise fashion from the luminal into the contraluminal plasma membrane, the fenestrae at the fracture edge involved both plasma membranes. Similar configuration of fenestrae was evident in the capillary endothelium of the rat pituitary. The fenestrae in the chromophobe adenoma were much less frequent than in the normal rat pituitary. The plasmalemmal vesicles occurring in replicas on one side of the cell did not appear to open to the other side of the cell. When the fracture followed the contours of the attached plasmalemmal vesicles, they appeared as smooth depressions in face A and domes in face B. When the fracture did not follow the contours of the vesicles, they were revealed as holes or depressed circular plaques in face A and broken-off necks or circular constellations of particles in face B. The plasmalemmal vesicles were more abundant and obvious in the tumour than in the normal rat pituitary.
Published Version
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