Estradiol-Induced Differentiation of the Oviductal Epithelium in Ovariectomized Cats

The effect of 17�3-estradiol on the oviductal epithelium of ovariectomized cats was studied by light and electron microscopy. Estradiol was administered by implantation of a silastic capsule containing crystalline 17j3-estradiol. Two months after ovariectomy the epithelial cells were atrophied and nonciliated. Estradiol treatment resulted in hypertrophy, mitotic activity and partial differentiation of both the nucleus and cytoplasm during days one to three. This differentiation included the conversion of chromatin from a condensed to a dispersed state along with the appearance of a distinct nucleolus, and an increase in the amount of polyribosomes, mitochondria, Golgi apparatus and short profiles of smooth endoplasmic reticulum. Ciliogenesis was found to be a multiphase process which occurred primarily on days two through five of estrogen treatment. Fibrogranular aggregates and patches of fibrous granules were evident in the apices of the future ciliated cells on day two. Procentrioles and basal bodies in various stages of development were found associated with either deuterosomes or diplosomal centrioles on days three and four. On day four mature basal bodies were either arranged in linear fashion at the apical border or were already aligned giving rise to ciliary buds and short cilia. After seven days of estrogen treatment 60 percent of the epithelial cells were ciliated. The remaining cells possessed abundant cisternae of endoplasmic reticulum and appeared to be differentiating into secretory cells. After 10 to 14 days, these cells possessed a large Golgi apparatus, dilated cisternae of endoplasmic reticulum and scattered apical secretory granules. This study clearly demonstrates that 1 7�-estradiol can restore the oviductal epithelium of the ovariectomized cat to a fully differentiated state, and that the mode of basal body and cilia formation is essentially the same as in the oviducts of various other species.