Aspectos da dinâmica folicular na égua.

Abstract

The equine specie has a low fertility due to the methods used to make their selection, as physics ability and the morphology, forgetting the reproductive characteristics. This work aimed to make a literature revision, emphasizing the main mechanisms that occur during the follicular dynamic in the mare, since the oogenesis, discussing the folliculogenesis, follicular waves, divergence, atresy and ovulation, besides to demonstrate the hormonal relations existents in this complex process, facilitating a best elucidation to a possible manipulation of the follicular development in equines. The oogenesis begins during the fetal development, where are formed the oocytes, witch be standing in repose till the begin of the puberty, in the folliculogenesis follicles grow, mature and even are selected to the ovulation, some valuation show that approximate 99% of the ovarian follicles suffer atresy, the follicular waves occur when many follicles grow in synchronicity. The mares usually present one or two follicular waves during the 21-22 days of the estrous cycle, the follicular divergence is characterized by the difference in diameter between the first biggest (F1) and second biggest follicles (F2), being observed the continue growth of F1 and the stabilization or reduction on the growth rate of the F2 and the other subordinated follicles. The atresy is usually considered an irreversible process, that occurs based in the cellular dead or apoptosis, the ovulation occurs after the divergence and selection of the dominant follicle, witch can reach approximate 40mm of diameter, moments before the ovulation. A complex interaction between the sexual hormones controlling the dynamic of the alterations suffered in the reproductive system and the sexual behavior, the main reproductive hormones can be grouped in gonadotrophins (LH, FSH and CG) and steroids (estrogens, progestin, and androgens) but other hormones have important functions in the female reproduction, as inhibin, oxytocin, melatonin, prostaglandin and relaxin. Through of the understanding these all reproductive mechanisms it is possible to reach success in the manipulation of the follicular development in mares.