INTRAGONADAL REGULATION OF FOLLICULAR DEVELOPMENT AND OVULATION

Ovulation rate, the major determinant of prolificacy, is determined by genotype and influenced by environmental factors and is the culminati on of folliculogenesis. Control of folliculogenesis lies with the gona dotropins and local regulatory factors in the ovary such as steroids, cytokines and growth factors. This review summarizes a functional mode l of folliculogenesis, and discusses evidence pertaining to it and to the regulation of ovulation rate, using data in ewes, cows and rats. P articular emphasis is placed on the roles of local regulators in the a cquisition and modulation of responsiveness of ovarian cells to gonado tropins, and their roles in proliferation and differentiation. Two mec hanisms of determining multiple ovulation are reviewed and applied to known states of prolificacy in sheep and cattle.