Altered progesterone/estrogen receptor ratios in endometriosis. A comparative study of steroid receptors and morphology in endometriosis and endometrium

In a comparative study of endometriosis and endometrium, specimens were taken from both endometriotic and endometrial tissue in 14 patients. Receptor assays and histological examinations were performed on both specimens. Cytosolic estrogen receptors (ERc) as well as cytosolic progesterone receptors (PRc) were detected in 9/14 and 12/12 cases of endometriosis respectively. Nuclear estrogen receptors (ERn) were detected in 4/4 cases of endometriosis. Expressed as fmol/mg cytosol protein, significantly higher values of both ERc and PRc were found in endometrium than endometriosis (p less than 0.01). However, when the ratio between PRc and ERc was considered, significantly higher PRc/ERc ratios were found in the cytosol of endometriotic tissue (p less than 0.01). Thus the lower receptor concentrations found in endometriosis cannot be explained solely as ectopic endometrium being diluted by nonreceptor-containing tissue. In spite of high PRc/ERc ratios in endometriosis, secretory changes similar to those found in endometrium were observed in only one of 7 cases (p less than 0.05).