Progesterone antagonism of estrogen-induced cytodifferentiation in chick oviduct.

Progesterone administered with estrogen to the intact female chick antagonizes the characteristic effects of estrogen to induce cell proliferation and cytodifferentiation of tubular gland cells in the oviduct, events that are accompanied by the appearance of lysozyme. Progesterone appears to exert its effect by preventing proliferation of cells destined to become tubular gland cells, but once such cells do proliferate, subsequent cytodifferentiation and appearance of lysozyme are not prevented.