Oviducts were obtained from women who elected to undergo sterilization either during a normal menstrual cycle, after the first trimester of pregnancy, or in the puerperium. The percent of ciliated cells, cell height and morphology of the fimbria and ampulla were determined and correlated with the stage of the reporductive cycle and plasma levels of the ovarian steroids. Mature ciliated and secretory cells were observed only at mid-cycle. Atrophy, deciliation and loss of secretory activity coincided with elevated levels of serum progesterone. These degenerative processes continued during pregnancy. Ciliation, hypertrophy, and restoration of secretory activity occurred when serum progesterone was essentially undetectable and estradiol relatively low. During each menstrual cycle the secretory cells were observed to undergo a complete cycle of dedifferentiation-differentiation, whereas 10--12% of the ciliated cells lost and regenerated their celia. Ciliogenic cells were frequently present in the epithelium obtained from women in the mid-follicular phase. Fibrous granules, deuterosomes, procentrioles and ciliary buds were observed in the apex of these cells. Plasma levels of estradiol were higher during periods of atrophy and deciliation than they were during periods of hypertrophy and reciliation. It appears that the serum levels of estradiol were adequate to maintain a mature epithelium at all the reproductive stages included in this study. However, progesterone, when present, blocked the growth-promoting effect of estradiol in the oviduct.
The control of the secretory cell cycle by estradiol and progesterone in the oviduct of the cat was studied using light and electron microscopy. The epithelium in ovariectomized animals was cuboidal with no evidence of secretory activity. Estradiol treatment induced hypertrophy, hyperplasia, and the differentiation of both secretory and ciliated cells. Differentiation of the secretory cell included the development of an extensive area of basal rough endoplasmic reticulum and a large supranuclear Golgi region. Apical secretory granules were already present after 3 days of estradiol treatment, and after 4 to 5 days maximum hypertrophy and differentiation had occurred. Most cells contained several apical electron-dense granules; however, no large accumulation of granules in any one cell was ever observed. Occasional release of secretory product by exocytosis occurred during chronic treatment with estradiol. Rapid elevation of the serum levels of estradiol or progesterone by means of IV injection did not enhance exocytosis or result in any ultrastructural alterations. The chronic administration of progesterone to estradiol-primed animals resulted in rapid cell atrophy, dedifferentiation, and death (apoptosis) within the epithelium of the oviduct. Secretory granules were no longer observed after 2 days of estradiol and progesterone treatment, and after 7 days the epithelium was approximately the same height as that measured in ovariectomized animals. These data illustrate that estradiol induces the differentiation and maintains the mature state of the secretory cell within the oviductal epithelium of the cat, and that progesterone has an immediate antiestrogenic effect on these cells. This study also suggests that the secretory product is released gradually, as the granules form and mature during chronic estradiol administration.
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