In situ hybridization of ovalbumin mRNA in the chick oviduct reveals target cell specificity for estrogen and progesterone.

An in situ hybridization method using paraffin-embedded sections was used to characterize the chicken oviduct cells synthesizing ovalbumin mRNA due to the action of estrogen and progesterone. The cytodifferentiation of the oviduct cells was induced by 17 beta-estradiol administration to newly hatched female chicks. To avoid possible effect of estrogen on the action of progesterone the chicks were withdrawn from the estrogen by six days withdrawal period without hormone treatment. Ovalbumin mRNA was not synthesized after a period of estrogen withdrawal. Administration of estrogen induced ovalbumin mRNA in the tubular gland cells. Administration of progesterone induced the expression of ovalbumin mRNA in the surface epithelial cells. It was also found that progesterone induced mucus producing goblet cells in the surface epithelium. Estrogen did not have an effect on the mucus production, which suggests that progesterone could induce the terminal differentiation of the goblet cells. We conclude that the expression of ovalbumin in the surface epithelial cells and in the tubular gland cells is specific for progesterone and estrogen, respectively.

The effect of dihydrotestosterone on the estrogen-induced cytodifferentiation of the chick oviduct.

The androgenic effects on the estrogen-induced cytodifferentiation of the chick oviduct epithelium were investigated. Dihydrotestosterone was shown to have an effect on the organization of stromal cells. Since these cells contained androgen receptor (AR), it is reasonable to assume an involvement of androgens in the differentiation and functioning of these cells through a direct action. Immunohistochemical analysis revealed a wide distribution of AR. AR was shown to be expressed in both the endothelial and smooth muscle cells of blood vessels. In the immature oviduct AR was located in the epithelial, mesenchymal and mesothelial cells. In the differentiating oviduct, whether induced by exogenous estrogen or normally by endogenous hormones, AR was also expressed by the tubular gland cells. Dihydrotestosterone alone had no effect on the morphology of the immature oviduct, suggesting the involvement of the determinants of differentiation in the action of androgen together with estrogen.

Progesterone receptor is constitutively expressed in chicken intestinal mesothelium and smooth muscle.

We have previously shown that progesterone receptor (PR) is expressed in the mesothelium of the chick oviduct and ovary and in the smooth muscle cells of the oviduct and the bursa of Fabricius. Here, we investigated the presence of PR in different parts of the peritoneum and abdominal organs using an immunohistochemical staining based on monoclonal antibodies against chicken PR. In 4-week-old sexually immature chicks, PR expression was located in the mesothelial cells of different parts of the peritoneum, in a thin layer of muscle cells of the ileum and throughout the muscle tissue of the colon and cloaca. In chicks of the same age treated with estrogen, PR was demonstrated similarly in the peritoneum and in the smooth muscle cells of the ileum, colon and cloaca. Using 25-week-old mature chickens, PR was also detected in identical tissues. Immunoblotting of the cloacal cytosol revealed the B form, but no A form of PR, both of which were found in the oviduct samples. Muscle cells of the duodenum and jejunum were not found to contain PR. Estrogen treatment was not needed to stimulate the production of PR in any of the tissues examined. We therefore conclude that the B form of PR is constitutively expressed in the mesothelial cells in different parts of the peritoneum and also in the smooth muscle cells of the ileum, colon and cloaca.