Progesterone receptors in human endometrium

Progesterone receptor levels were determined in the cytoplasm obtained from endometrial tissue of 21 patients. In normal women, the levels of progesterone receptors were related to the stage of the menstrual cycle with highest levels occurring in the early secretory stage. In the non-secretory endometrium 5 out of 11 patients had no detectable progesterone receptors. The absence of progesterone receptors may be related to the distribution of non-responders to progestogen therapy.