Immunohistochemical localization of 17 beta-hydroxysteroid dehydrogenase in the human endometrium during the menstrual cycle.

Immunoaffinity-purified polyclonal anti-rabbit antibody against human placental 17 beta-hydroxysteroid dehydrogenase (17HSD) was used to localize 17HSD in frozen sections of 21 human endometrial tissue specimens, taken at different stages of the menstrual cycle, and in the human placenta. The presence and distribution of estrogen and progesterone receptors were also analyzed in endometrial specimens using commercial immunohistochemical techniques. In addition, 17HSD was localized by immunoelectron microscopy in the endometrium and the placenta. In the endometrium, immunostaining of 17HSD appeared in the cytoplasm of surface epithelial and gland cells during the early and midluteal phase. During the late luteal phase, it gradually disappeared. No immunostaining was observed in the endometrium during the follicular phase of the menstrual cycle. The changes in staining intensity of 17HSD were associated with changes in the concentration of serum progesterone as judged by radioimmunoassay. An apparent inverse correlation between 17HSD expression and the concentrations of estrogen and progesterone receptors was observed. These results strongly support the concept that progesterone induces an increase in the amount of 17HSD, in the glandular and surface epithelial cells of the human endometrium. In the human term placenta, 17HSD immunostaining was detected exclusively in the cytoplasm of syncytiotrophoblasts. In immunoelectron microscopic studies of the endometrium and placenta, 17HSD staining was observed in the cytoplasm and it was associated with cytoplasmic membranes unrelated to the endoplasmic reticulum.