Distribution of intermediate filaments in epithelial cells of the amphibian urinary bladder: an immunofluorescence study.

The distribution of intermediate filaments in toad and frog urinary bladder was studied on frozen sections by indirect immunofluorescence microscopy using specific antiprekeratin antibodies. Our results show that in both species, epithelial cells lining the urinary bladder are very rich in cytokeratin, organized as a filamentous network. In granular cells, the most abundant cells facing the urinary lumen, vasopressin promotes fusion of the membranous tubular structures located in the luminal cytoplasm with the apical cell membrane. A role for intermediate filaments in the membrane rearragements induced by vasopressin in these cells, is proposed.