Estrogen receptor in rabbit endocervical cells isolated by velocity sedimentation.

Three nonciliated rabbit endocervical epithelial cell types were isolated by velocity sedimentation at unit gravity. Cell Types I and II contained heterogeneous secretory granules, whereas Type III cells were characterized by empty cytoplasmic vacuoles. Previous studies had confirmed the ultrastructural and functional integrity of each cell type and suggested hormone dependence of cell population sizes. Since the concentration of total cytosol estrogen receptor in endocervical epithelial cells from progesterone-dominated, 5-day pseudopregnant rabbits was reduced to approximately 23% of the value for estrous rabbits, receptor concentrations were measured in the three nonciliated epithelial cell types from animals in both hormonal states. The results indicate that the reduction in the estrogen receptor content in progesterone-dominated animals can be attributed to a reduction in the number of Type I and Type II cells, and to a significant (P less than 0.05) reduction in their estrogen receptor concentrations.