Effects of medium composition and progesterone on maturation in vitro of rabbit oocytes from Graafian follicles of different sizes.

Abstract

Rabbit oocytes from large (1-1.5 mm diam.), medium (0.5 mm) and small (0.15-0.25 mm) antral follicles were cultured in five chemically defined media. In all media, oocytes from large antral follicles showed the highest incidence of meiotic activity followed by those from follicles of medium size. Most oocytes from small follicles did not resume meiosis in culture. The addition of glutamine to a standard medium for ovum culture significantly improved maturation of oocytes from medium-sized follicles but did not affect those from large or small follicles. When polyvinylpyrrolidone was substituted for bovine serum albumin, maturation of oocytes from large and medium-sized follicles was reduced. Progesterone at a concentration of 10 micrometer did not affect maturation, but 100 micrometer-progesterone blocked germinal vesicle breakdown in oocytes from medium-sized follicles and reduced both germinal vesicle breakdown and polar body formation in oocytes from large follicles. This effect was reversible.