Regional differences in the ultrastructural features of secretory cells in the golden hamster (Mesocricetus auratus) oviductal epithelium.

The secretory cells of the golden hamster (Mesocricetus auratus) oviductal epithelium on the day of ovulation were observed by light and electron microscopy. In the fimbriae two types of secretory cells were observed: one possessed secretory granules with electron-lucent matrices, prominent protrusions and many electron-dense granules resembling lipid droplets, and the other possessed many secretory granules with moderately electron-dense, homogeneous matrices, occasionally containing an electron-dense area. The former type was only observed in the fimbrial epithelium, while the latter was present in both the fimbriae and the infundibulum. In the ampullary and isthmic cells many secretory granules with moderately electron-dense, homogeneous matrices were observed in the supranuclear area. Electron-dense areas were frequently observed in many secretory granules of the isthmic cells. Lysosome-like vesicles, partly filled with a dense substance and/or a finely granular substance, were observed in the infranuclear cytoplasm of the isthmic cells. Fusion between vesicles and secretory granules was frequently observed. These ultrastructural observations of the golden hamster oviduct reveal marked regional differences in the morphological features of secretory cells. These results may provide insight into regional and cellular differences in the function of the oviduct.