The Microenvironment of the Human Antral Follicle: Interrelationships among the Steroid Levels in Antral Fluid, the Population of Granulosa Cells, and the Status of the Oocyte in Vivo and in Vitro *

Abstract

A number of parameters in human antral follicles were investigated. They were: the number of granulosa cells in each follicle; the concentrations of progesterone, androstenedi-one, testosterone, dihydrotestosterone, estrone, and 17β-estra-diol in antral fluid; and the status of the oocyte immediately after removal from the follicle and again after 48 h in culture. In addition, the phase of the menstrual cycle at the time of ovariectomy and the diameter of each dissected follicle were recorded. The number of granulosa cells present in each follicle and the viability of the oocyte before culture as well as its subsequent in vitro behavior were correlated with the concentration of estra-diol and⁄or the ratio of androgen to estrogen in antral fluid. It is tentatively suggested that follicles with a potential for further development are those with 1) more than 50‰ of their full complement of granulosa cells for their respective diameters, 2) high concentrations of 17β-estradiol (≥1000 ng⁄ml) in their antral fluid and⁄or granulosa cells with the capacity to generate this steroid in response to FSH, and 3) a germinal vesicle stage oocyte which appears healthy at the dissecting microscope level. Follicles incapable of further development are suggested to be those containing 1) less than 50‰ of their full complement of granulosa cells for their respective diameters and 2) low concentrations of 17β-estradiol in their antral fluid and granulosa cells incapable of responding to FSH to ge…