Estrogen and progesterone cytosol receptor concentration in endometriotic tissue and intrauterine endometrium.

Cytosol estrogen (ER) and progesterone (PR) receptors were assayed in peritoneal and ovarian endometriotic tissue from 20 patients. In 12 of the cases the intrauterine endometrium was assayed as well. The control material consisted of normal endometrium from 30 women. The receptor content of the endometriotic tissue was less than that of the endometrium of the same patient. In most cases no receptors could be detected (12/20 cases ER-, 7/9 cases PR-) irrespective of the phase of the menstrual cycle. The endometrial receptor concentrations were that same in patients with endometriosis as in the control group. There were no differences in binding characteristics of the receptors in the two tissue types. It is concluded that endometriotic tissue contains lower a concentration of cytoplasmic ER and PR than the normal endometrium.