ABSTRACT
The entire process of follicle growth can be conveniently divided into: 1) the organization of primordial follicles and the early growth of primary follicles, the latter of which may persist for years; 2) the recruitment of primary follicles into the slow growth phase (the prehierarchal or previtellogenic stage) lasting weeks to perhaps months; and 3) the selection and rapid growth of preovulatory follicles which occurs during the final days preceding ovulation. The continued viability and development of ovarian follicles within a breeding season is critically dependent upon endocrine factors (e.g., gonadotropins) circulated by the blood, paracrine and autocrine factors produced within the ovary itself, plus neurochemical and neurohumoral factors expressed by the nervous system.
