Formation of misplaced and reflexive tight junction strands in prostate epithelial cells.

Tight junction strands occur at three atypical locations in slices of rat ventral prostate exposed to conditions promoting rapid tight junction assembly: (1) in the basal plasma membranes of the columnar epithelial cells, over 40 microns from the native apical tight junction band (misplaced tight junctions); (2) in the plasma membranes of basal epithelial cells, which never have tight junctions in the native state; and (3) between processes of the same cell (reflexive or autocellular tight junctions) at the basal or lateral portions of the columnar epithelial cell. These findings suggest that tight junction formation is not limited to specific parts of the plasma membrane, even in highly polarized cells such as those in prostate epithelium. Taken together with other new evidence, they also suggest that tight junctions may be very labile.