[The progesterone receptor in the chicken oviduct: double disclosure by immunohistochemistry with antireceptor antibodies and autoradiography with tritiated progestin].

Explants of estradiol primed Chicken oviduct were incubated with a tritiated synthetic progestin (3H-Org 2058). Frozen sections were processed either for autoradiography, or for immunohistochemistry with two different antibodies to the progesterone receptor, or, for the first time, by the two techniques combined on the same section. In all cell types (glands, luminal epithelium, stroma, mesothelium and muscle fibers) where the tritiated hormone was concentrated in the nuclei, the receptor was also recognized in the nuclei by both antibodies. In the center part of the explants, cells did not show radioactive nuclear labeling, though the nuclei displayed the same intensity of reaction with the antibodies as external cells. This result suggests the presence of progesterone receptor in nuclei of target cells even in absence of progesterone. The same combined double hormonal and immunological evidence of progesterone receptor was obtained in pituitary cells of a chicken injected with 3H-Org 2058.