The effect of intrauterine progesterone on the DNA-content in isolated human endometrial cells

The effect of an intrauterine progesterone-releasing device on the DNA-content in human endometrial cells has been studied by means of a microfluorometric method. Following six of seven months' use of the progesterone-releasing device a significant decrease in the mean DNA-content per cell nucleus was found in the epithelial cells indicating a suppression of the proliferative activity of the endometrium. The mean DNA-values of the endometrial cells remained at a low level throughout the cycles in spite of circulating levels of steroids indicating a normal ovarian function. It is suggested that the progesterone released in utero interferes with the DNA-synthesis of the epithelial cells, which may result in a disturbed metabolic function of the endometrium at the time of implantation.