Nuclear estrogen receptor bindings in granulosa cells and estradiol-17 beta contents in follicular membranes of the ovary of the hen during the ovulatory cycle.

Estrogen receptors were found in the nuclear fractions of granulosa cells of the largest (F1) and the second largest (F2) preovulatory follicle in the ovary of the hen. The maximum number of binding sites (NBSmax) of the nuclear estrogen receptors was greater in F2 than in F1, while the equilibrium dissociation constant (Kd) was not different. During the ovulatory cycle, the NBSmax of the estrogen receptors showed a change parallel to the change in the estradiol-17 beta content in the follicular membranes. The results suggest that estradiol-17 beta produced in the follicular membrane may exert a direct action on the granulosa cells in the hen ovary.