Distribution of total progesterone receptor levels in various segments and tissues of the normal human uterus: the effect of short-term estrogen administration.

Total progesterone receptor levels (TRP) were measured in various tissues and segments of normal human uteri in basal conditions (late proliferative phase, control group, n = 6) and after short term estrogen administration (test group, n = 8). Similar trends of distribution were observed in both groups in basal endometrial TRP levels along the longitudinal axis, i.e. the highest levels were found at the height of the body and the lowest at the height of the internal os. Differences were found in the trends of distribution of the TRP levels between the two groups along the transverse axis of the uterus at the height of the fundus. In the control group TRP levels in the functional endometrium were higher than those in the basal endometrium and myometrium. In the test group, however, the trend was reversed. Since the RP is estradiol induced and dependent, these results indicate the possibility of a selective estrogen effect on various segments or tissues in the human uterus.