Menstrual Cycle: Follicular Maturation

Abstract

As might be expected, the teleological underpinning of ovarian function draws on the fundamental need to preserve the species. Accordingly, the very existence of the ovary, and for that matter the very existence of the reproductive axis as a whole, is designed to subserve a single central objective, i.e., the generation of a mature fertilizable ovum. In this respect the ovary clearly need not be viewed as playing a secondary role in reproductive biology. Rather, it may be viewed as the “master gland” the very function of which is facilitated by the contribution of the various other components of the hypothalamic-pituitary-ovarian axis. This view differs of course from the more traditional outlook ascribing the role of a “master gland” to the pituitary, the workings of which are highly dependent on hypothalamic principles. However, current information would suggest that the ovary may in fact play an active rather than a passive role in the initiation and maintenance of reproductive cyclicity, the hypothalamus and pituitary being viewed as playing a permissive tonic role in this connection. Indeed, it is the changing tide of ovarian signals that appears to determine to a large extent the nature of the activities of the hypothalamic-pituitary unit. It is for these reasons that the ovary has often been likened to a pelvic clock (“zeitgeber”) dictating in more ways than one the comings and goings of the reproductive process. Stated differently, consideration might be given to the argument that the ovary does, in effect, possess a “mind” of its own, as attested to by a multitude of putative intraovarian regulators, the very action of which is highly reminiscent of events previously viewed as the domain of the central nervous system.