Further freeze-fracture studies on the uterine epithelium of Salamandra salamandra (L.) (Amphibia, Urodela) using the antibiotic filipin.

The apical portion of the uterine lining of the ovoviviparous fire salamander, Salamandra salamandra, was studied by the freeze-fracture technique in conjunction with the polyene antibiotic filipin. Filipin-sterol complexes were found in the luminal plasmalemma and in the membranes limiting the mucous secretory granules typical of this epithelium. In all females, but particularly in non-pregnant females, more or less discrete clusters of filipin-sterol complexes were occasionally found overlying heavily affected secretory granules. The findings are discussed with regard to comparable results (Orci et al. 1980) based on the examination of collapsed and stretched urinary bladders of toads.