Abstract
We examined the ultrastructural features of secretion by the murine oviductal epithelia. In ampullae, mucus material accumulated in the apical parts of the secretory cells in proestrus, estrus and metestrus. In estrus and metestrus, numerous secretory granules of various sizes were seen. Fusion of secretory granules and the plasma membrane, i.e. exocytosis, was observed in metestrus. In diestrus, however, the secretory cells were atrophied. Secretory products from the ampullar epithelium may support fertilization and embryonic development in early stages. At the isthmuses, largely-expanded rough endoplasmic reticulum was seen in metestrus. Secretory granules were observed in proestrus and estrus, and these were released by exocytosis especially in proestrus. The material contained in these granules may play an important role in sperm capacitation. The present results indicate that the secretory cells of ampullae and isthmuses are regulated differentially by the estrous cycle dependent factors in mice.
