Immunohistochemistry was used to determine the distribution of oestrogen receptors (ER) and progesterone receptors (PR) in the human ovary during folliculogenesis. Primordial and preantral follicles did not contain ER or PR. The granulosa cells of antral follicles had ER, but negligible PR, before the LH surge. In contrast, at the time of LH surge, these cells of the dominant follicle contained PR, but not ER. On the other hand, granulosa cells of the non-dominant follicles had ER, but not PR. After ovulation, the PR persisted in the luteinized granulosa cells and in the corpus luteum during early pregnancy. The theca interna and surrounding stromal cells were ER-negative and PR-positive throughout the menstrual cycle. Thus, the results show that ER and PR are not expressed simultaneously in the granulosa cells, the thecal cells, or the stromal cells during folliculogenesis. Mechanisms controlling the expression of steroid receptors during the normal menstrual cycle and in early pregnancy are discussed.

Immunohistochemical distribution of oestrogen receptors (ER), progesterone receptors (PR), and the cell proliferation-associated antigen Ki-67 was investigated in leiomyomas and the myometrium during the menstrual cycle and pregnancy. In the myometrium, ER expression was observed in the proliferative phase, but was suppressed in the secretory phase and during pregnancy. In leiomyomas, ER expression was observed throughout the menstrual cycle, but was suppressed during pregnancy. However, PR was expressed both in the myometrium and leiomyomas throughout the menstrual cycle and pregnancy. In both the myometrium and leiomyomas, a higher number of Ki-67-positive cells was observed during pregnancy than in the secretory phase, and Ki-67 was negative during menopause. The Ki-67-positive cell count in leiomyomas was significantly higher than that in the myometrium throughout the menstrual cycle and pregnancy. Thus both myometrium and leiomyomas have high growth activity under the hormonal milieu of high progesterone levels. The growth potential of leiomyomas is apparently higher than that of myometrium throughout the menstrual cycle and during pregnancy.

To investigate the relationship between the sex steroid receptor (estrogen receptor [ER] and progesterone receptor [PR]) status and the cell proliferation kinetics during the menstrual cycle in normal and neoplastic epithelium of the uterine cervix, immunohistochemical localization of ER, PR, and cell proliferation‐associated antigen, Ki‐67, was investigated in 35 normal cervical specimens, 3 condylomas, 26 cervical intraepithelial neoplasia (CIN) samples, and 22 invasive squamous carcinoma samples. The presence of human papillomavirus (HPV) DNA was also studied. In the normal cervix, basal cells were usually ER positive, PR negative, and Ki‐67 negative throughout the menstrual cycle. Parabasal cells were ER positive and PR negative in the follicular phase, but ER negative and PR positive, and Ki‐67 positive in the luteal phase, and Ki‐67‐positive cells increased in number in the luteal phase. In contrast, PR positivity was observed in the cells of condyloma (2 of 2 cases), CIN (19 of 26 cases), and invasive squamous carcinoma (13 of 22 cases) irrespective of the menstrual phase, Moreover, most neoplastic cells containing HPV DNA type 16/18 were ER negative, whereas several lesions containing HPV DNA type 31/33/35 were weakly ER positive. Many Ki‐67‐labeled cells were observed in the neoplastic lesions. These results suggest that reduced ER expression and increased PR expression are associated with the proliferation of normal cervical squamous epithelium, and this proliferation‐related receptor status, which is probably induced by HPV infection, is usually expressed in neoplastic cervical squamous cells.

To investigate whether LH/human CG (hCG) or progesterone acts as a regulator of estrogen receptors (ER) and progesterone receptors (PR) in granulosa cells, we studied the immunohistochemical expression of both ER and PR in the ovary and the uterus of mature rabbits, during the induction of ovulation by FSH followed by administration of hCG, progesterone, or a progesterone antagonist (RU486) and hCG. Granulosa cells pretreated with FSH for 3 days showed ER staining, but negligible PR staining. The staining pattern for ER and PR changed in animals pretreated with FSH followed by hCG injection; by 6 h after hCG injection, we observed the disappearance of ER and the appearance of PR, and by 3 days after hCG injection, we observed the reappearance of ER and the disappearance of PR. However, the expression of ER and PR in the granulosa cells of animals pretreated with FSH followed by progesterone administration instead of hCG was almost the same as that of animals pretreated with FSH alone. In addition, the expression of ER and PR in the granulosa cells of animals pretreated with FSH followed by RU486 and hCG was almost the same as that of animals pretreated with FSH followed by hCG administration. The uterine glandular epithelium, in contrast, began to show decreased appearance of ER and PR by 48 h after hCG injection, and we observed the disappearance of both receptors by 3 days after hCG administration. These results suggest that the expression of ER and PR in granulosa cells is not regulated by the action of progesterone, but by that of LH/hCG.

The c-erbB-2 (HER-2/neu) protein is a membrane glycoprotein growth factor receptor that has molecular homology with the epidermal growth factor receptor (EGFR). To investigate the relationship between the expression of c-erbB-2 protein and EGFR in the tissues of the human female genital tract and in the placenta, we examined the immunohistochemical reactivity of monoclonal antibodies against both of these proteins. In the müllerian-derived genital tract, epithelial cells of the fallopian tube, endometrium, and endocervix showed reactivity for c-erbB-2 protein, whereas reactivity for EGFR was distributed mainly in the stromal cells throughout the menstrual cycle and during pregnancy. In addition, the staining intensity for EGFR in the endometrial stroma increased with its decidualization. In the exocervical squamous epithelium, basal cells were c-erbB-2 protein-negative and EGFR-positive, but the more differentiated squamous cells of the intermediate layer were c-erbB-2 protein-positive and EGFR-negative. In the placental tissues, cytotrophoblasts and syncytiotrophoblasts of the chorionic villi were c-erbB-2 protein-negative and EGFR-positive. In contrast, intermediate trophoblasts in the extravillous space were c-erbB-2 protein-positive and EGFR-negative. Thus, there is an inverse relationship between the expression of c-erbB-2 protein and EGFR in the tissues of the female genital tract and in the placenta. This suggests that there may be a regulatory mechanism(s) for the expression of both proteins that is associated with the differentiation and/or function of cells in the female genital tract and the placenta.