Ultrastructural and ultracytochemical features of secretory granules in the ampullary epithelium of the hamster oviduct

The epithelium of mammalian oviducts consists mainly of ciliated and non-ci liated secretory cells. In some mammals, secretory products originating fro m oviductal secretory cells have been shown to bind to the surface of, or a ccumulate within, ovulated eggs and/or developing embryos. These findings s uggest that the secretions of the oviductal epithelial cells may play an im portant role in reproductive and developmental events that occur in the ovi duct. In the present study, ultrastructural and cytochemical features of secretor y cells in the hamster ampullary epithelium were shown by routine electron microscopy, lectin-gold cytochemistry and both conventional freeze-fracture and rapid-freezing techniques with special reference to the organizational aspects of their secretory granules. The use of ferrocyanide-reduced osmiu m tetroxide as a post-fixative in the Epon embedment of ampullary tissue sa mples also proved to be advantageous especially in revealing the carbohydra te contents of certain cellular compartments. The most conspicuous characte ristic of the secretory cells, based on their staining property, was the pr esence of two types of secretory granules: those with a homogeneous electro n-dense matrix and those with an electron-lucent matrix. Under favorable co nditions, distinct features of the organizational arrangement of a crystall ine lattice inside the secretory granules were also revealed. This well org anized crystalline lattice shown in sections of Epon-embedded oviductal tis sue was confirmed by examination of replicas of freeze-fractured oviducts p repared by the rapid-freezing technique. We also demonstrated with high res olution lectin-gold cytochemistry the intracellular distribution of lectin- binding glycoconjugates in the secretory cells of the hamster oviductal amp ulla often in a linear array following the crystalline lattice. The results obtained in this study, taken together, provide insight into a possible link of the internal topographical features of oviductal secretory granules along with the cytochemical properties of their contents to the a nticipated regulatory mechanism underlying their process of secretions. Ana t Rec 255:227-239, 1999. (C) 1999 Wiley-Liss, Inc.