Qualitative changes in medium and large antral follicles in the human ovary during the menstrual cycle

Abstract

To better understand human ovarian folliculogenesis, we analyzed 370 (medium and large) follicles from the ovaries of 33 women aged 18 to 50 years at various stages of the menstrual cycle. These follicles were grouped according to granulosa cell number. The criteria used for distinguishing between healthy and atretic follicles were the pyknotic index and the nuclear status of the oocyte, completed by other parameters of follicular involution. The mean mitotic index of the follicles did not vary with the stage of the menstrual cycle, except for those having between 0.37 x 106 granulosa cells during the late luteal phase. In humans, a species with a long follicular phase, the qualitative kinetics of medium and large antral follicles did not seem to support any particular theory of a wave of folliclar development. It is suggested that follicular growth is a continuous process with privileged phases during the menstrual cycle, especially in the late luteal phase when medium antral follicles are less apt to involute and grow faster.