Freeze-fracture study of rat ventral prostate: the columnar epithelial cell.

The organization of the secretory epithelium of the rat ventral prostate as seen by freeze-fracture is analyzed. Ultrastructural interpretation of the tall columnar epithelial cell is facilitated by the axial regionalization of the cytoplasm. The endoplasmic reticulum, which exists in all the regions of the cell, appears to have a role in the maintenance of cellular organization. Its cisternae delimit the spaces for the nucleus, the Golgi, and the apical secretory apparatus. Elements involved in the formation of secretory products for export are located within the apical region of the cell and are regionally separated from the Golgi complex. Structural and functional specializations of the plasma membrane in the apical, lateral, and basal areas are illustrated. Artifacts related to specimen preparation procedures are reported. Displacement of membrane particles, which we observed in the fracture faces of plasma and intracellular membranes, appears related to fixation at low temperature. Fixation at 37 degrees C, which does not induce membrane-particle displacement, results in proliferation of tight-junctional elements.