[Variations in the estradiol and progesterone receptors in human endometrium during the menstrual cycle]

The concentration of estradiol and progesterone "receptors", both cytoplasmic and nuclear, has been measured in human endometrium during the menstrual cycle using an exchange assay method. A rapid increase of the concentration of the two "receptors" has been observed during the proliferative phase followed by a striking decrease during the secretory phase. New physiological and pharmacological aspects may be derived from these results.