The regulation of follicle growth: some clinical implications in reproductive endocrinology

To review the literature concerning the regulation of follicle growth, to describe a model for unifollicular ovulation based upon the information gleaned, and to discuss some clinical implications in reproductive endocrinology underscored by this expanding knowledge. Studies relating to follicular growth in lower animals and primates were reviewed. From the most pertinent articles the individual agents playing a significant role in the regulation of follicle growth were identified along with their mechanisms of action. A model for unifollicular development was proposed based upon the results of the review of these studies. Refinements in the management of some clinical problems in reproductive endocrinology were discussed based upon this model. From a review of these studies it appears that in the human and primate menstrual cycle one follicle is selected because it has adequate FSH receptors when plasma FSH levels are high. This follicle becomes dominant despite falling FSH levels because of increased sensitivity of the follicle to FSH brought about by intraovarian growth regulators. Improved care of patients requiring ovulation induction for differing indications should be possible with this more comprehensive knowledge of natural follicle growth.