Vol. 7, Issue 11 (2018)

Author(s):
Bhuvana Plakkot, Shiji Sheeja Saju and Raji Kanakkaparambil

Abstract:
In all mammals, release of gonadotropins is a pulsatile process which appears to be the result of periodic secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus into the pituitary portal circulation. Follicle-stimulating hormone (FSH) and Leutinizing hormone (LH) are gonadotropins discharged by the pituitary gland that coordinate antral folliculogenesis and ovulation in female ovaries. Wave-like ovarian follicular growth pattern is observed in cattle, sheep, goat, horse and human. In the follicular phase of estrus cycle, several antral follicles undergo atretic degeneration, while only very few progresses towards ovulation. Every follicular wave includes recruitment, selection and dominance phases. The recruitment and selection processes govern the number of ovulatory follicles in these species with FSH and eventually LH playing prime roles. Through the postive and negative feedback mechanisms with the hypothalamo-pituitary axis, these hormones provide the basic process that regulates follicular recruitment, selection and dominance. Along with the adjustment of threshold levels of these hormones, differentiation between monovulatory and polyovulatory species is defined and thereby these hormones play a major role in prolificacy.