ABSTRACT
The presence and changes of estradiol nuclear binding and related functions in uterine luminal and glandular epithelium were studied before and after blastocyst implantation using receptor autoradiography with (3)H-estradiol-17beta in association with (3)H-thymidine incorporation and immunocytochemical binding of antibody to estrogen receptor ER-alpha. (3)H-estradiol nuclear binding is present but variable during days 1.5-7.5 of pregnancy. Sites of strong nuclear binding of (3)H-estradiol exhibit strong immunocytochemical staining with ER-alpha antibody. Qualitative and quantitative evaluation of autoradiograms reveal that there is a general increase of nuclear (3)H-estradiol binding during the first 3 days after fertilization in both luminal and glandular epithelium. The binding of estradiol is stronger in glandular epithelium from day 2.5 to day 7.5, paralleled by a rise in (3)H-thymidine incorporation on day 2.5. By comparison, in the epithelium of the uterine lumen (3)H-estradiol nuclear binding is low, but relatively high in epithelial cells at lateral branching of the lumen where the increase in (3)H-estradiol binding corresponds to an increased labeling index with (3)H-thymidine. A highly differentiated binding of (3)H-estradiol to luminal and glandular epithelium was demonstrated with region- and time-specific changes of related effects on cell proliferation, differentiation, and secretion, probably involving involution and remodeling. The strong (3)H-estradiol binding to glandular epithelium suggests that estradiol exerts pronounced effects on glandular activities in the periimplantation period.
