Is progesterone the key regulatory factor behind ovulation rate in sheep?

Ovarian antral follicles in the ewe grow in an orderly succession, producing 3 to 4 waves per estrous cycle. In prolific sheep, some large antral follicles from the second-to-last wave of the estrous cycle are added to the ovulatory follicles emerging just before estrus to give a higher ovulation rate; it is feasible that regression of these follicles is prevented by an increase in serum concentrations of FSH and/or LH pulsatility at proestrus. Prolific sheep tend to have a shorter luteal phase than nonprolific ewes, and there is a great deal of evidence that luteal progesterone (P4), in addition to regulating LH release, may govern the secretion of FSH heralding the emergence of follicular waves.

Source: Domestic Animal Endocrinology - June 27, 2016 Category: Endocrinology Authors: P.M. Bartlewski, J. Sohal, V. Paravinja, T. Baby, M.E.F. Oliveira, M. Murawski, T. Schwarz, D.A. Zieba, D.H. Keisler Source Type: research