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Chick oviduct differentiation. The effect of estrogen and progesterone on the expression of progesterone receptor
1Department of Biomedical Sciences, University of Tampere, Finland.
Insights
Estrogen induces progesterone receptor (PR) in chick oviduct cells, particularly mucosal stromal cells, which are crucial for epithelial differentiation. Ligand binding alone doesn't trigger progesterone-dependent responses.
Area of Science:
- Reproductive biology
- Endocrinology
- Cellular differentiation
Background:
- Progesterone receptor (PR) is a key marker of estrogenic action.
- Estrogen influences oviduct development and function.
- Understanding PR dynamics is crucial for reproductive research.
Purpose of the Study:
- To investigate the cellular localization and induction of PR during estrogen-mediated chick oviduct differentiation.
- To explore the role of PR in mucosal stromal cells in mediating epithelial differentiation.
- To examine the effect of progesterone on PR immunoreactivity and avidin synthesis.
Main Methods:
- Immunohistochemistry was used to detect PR cellular expression.
- Immature chick oviducts were treated with estrogen and progesterone.
- Changes in PR immunoreactivity and avidin synthesis were analyzed.
Main Results:
- PR was detected in epithelial, mesothelial, stromal, and smooth muscle cells of the oviduct.
- Estrogen induced PR expression in mucosal stromal cells, preceding tubular gland formation.
- Progesterone treatment decreased PR immunoreactivity without inducing avidin synthesis, indicating ligand binding is insufficient for induction.
Conclusions:
- Mucosal stromal cells play a critical role in mediating estrogen-induced epithelial differentiation via PR expression.
- PR expression is inducible and estrogen-dependent in mucosal stromal cells.
- Oviduct differentiation involves complex cellular interactions and hormonal signaling pathways.
Abstract:
Progesterone receptor (PR) is a marker of estrogen action. Its cellular appearance during estrogen (20 mg/kg i.m.)-induced differentiation of the immature chick oviduct was therefore studied by immunohistochemistry. PR was located in the epithelial, mesothelial, submucosal stromal and smooth muscle cells. Progesterone (20 mg/kg i.m.) caused an obvious decrease in PR immunoreactivity without inducing synthesis of progesterone-dependent avidin. Thus mere receptor occupation by ligand is not sufficient for this induction. This paper reports that the expression of PR in the mucosal stromal cell differs from that in other cell types. In the mucosal stromal cell PR was inducible, i.e., not shown without the action of estrogen. The formation of tubular glands did not commence before mucosal stromal cells expressed PR. It would seem that the mucosal stromal cells have a crucial role in mediating epithelial differentiation. The onset of differentiation was preceded by vascularization and invasion of mononuclear cells in the submucosa. It was conspicuous that the smooth muscle cells of arteries also contained PR.