Ultrastructure of the basal cell and the acinar capsule of rat ventral prostate.

The rat ventral prostate was fixed by perfusion and studied with the light and the electron microscope. In the light microscopy, few solitary basal cells appeared between the secretory epithelial cells and the capsule. In the electron microscopy, the basal cells lay among the secretory epithelial cells and on the acinar basal lamina, and their fine structural features were different from those of the ordinary secretory epithelial cells and rather resembled those of an undifferentiated secretory epithelial cells. Further the basal cells were characterized by the presence of the numerous pinocytotic vesicles and of the solitary cilia. The pinocytotic vesicles were also encountered in the capsular smooth muscle cells in the capillary endothelial cells which were located between the secretory epithelial cells and the acinar capsule. The amount of the cytoplasmic filaments in the basal cells was considerably smaller than in the myoepithelial cells.