Immunohistochemical study of distribution of estrogen receptors in corpus and cervix uteri.

An immunohistochemical assay based on monoclonal antiestrophilin antibodies has been used to localize estrogen receptor (ER) in frozen sections of normal human endometrial, myometrial and cervical tissues from menstruating, hormonally treated, pregnant and postmenopausal women. Specific staining was confined to the cellular nuclei. In proliferative phase endometrium, postmenopausal emdometrium, and endometrium from patients treated with hormone ERs were easily detected in most glandular and stromal cells. After ovulation and in early pregnancy a quick and distinct decrease of ER expression was noted. This was especially the case with the more superficial layers of endometrium (endometrium functionalis), the majority of whose cells had either weak localization of ER or none at all. In the endometrium basalis, however, the reduction of ER localization turned out to be more moderate. More then half of the epithelial and stromal cells displayed nuclear staining, partly strong. The myometrium of the corpus uteri showed a similar ER localization and dependence on hormonal stage when compared with the endometrium functionalis. The endocervical mucosa displayed a high degree of ER expression in the proliferative phase, in postmenopausal women and in women who had been treated with hormones. Unlike the endometrium and myometrium, the endocervical glands underwent minimal changes in nuclear ER content during the menstrual cycle. Although the endocervical stroma showed cyclic alterations in ER levels, their reduction after ovulation was less marked than in the corresponding endometria. In cervical squamous epithelium ER localization was predominantly confined to the basal layers. In the course of cellular maturation, specific nuclear staining vanished. In the proliferative phase, after the menopause and in early pregnancy, the basal, parabasal and intermediate cells were specifically stained. In the postovulatory phase, However, nuclear staining was confined to the basal and parabasal cells. Hormonally treated squamous epithelia almost completely lacked nuclear ER localization.