Preservation of the structural integrity of tight junctions during the freeze-fracture of ciliary epithelium.

It has recently been reported that losses of tight junction material could result from the freeze-fracture process. To verify this assumption, we tried to increase the possibility, if any, of losses of junction material, by inducing an important fragmentation of junctional fibrils by bathing ciliary epithelium in a 0.5M sucrose solution before glutaraldehyde fixation and freeze-fracturing at -160 degrees C. In spite of a significant redistribution of junctional material on both fracture faces, careful examination of complementary replicas and measurements of junction elements and interruption lengths showed that no loss of junctional material occurred in this tissue. The influence of physical parameters (i.e. temperature) on the preservation of the structural integrity of the tight junction during fracturing is now a problem to be considered.