Schematic representation of human follicle development during the follicular phase of the menstrual cycle. There are two major events in this process: increased sensitivity of a maturing follicle and selection of a single dominant follicle. In spontaneous cycles, this is achieved at the beginning of the cycle by a transient increase in serum FSH concentrations above some threshold value; the concentrations then decrease, preventing more than one follicle from undergoing preovulatory development.
E2: estradiol; FSH: follicle-stimulating hormone.
Fauser, BC, Van Hevsdeau, AM, et al. Manipulation of human ovarian function: Physiological concepts and clinical consequences. Endocr Rev 1997; 18:71.
