Quality of Preovulatory (GV) Oocytes in Mice after Injection of eCG at Various Stages of the Estrous Cycle.

We studied the influence of the estrous cycle on the morphology of preovulatory (germinal vesicle, GV) oocytes in mice and their capacity to meiotic maturation in vitro. After standard injections of eCG gonadotropin (PMSG, Follimag) to females at different stages of the estrous cycle, the maximum levels of GV oocytes (26±1/mouse) were isolated from the ovaries of animals injected with the hormone during estrus. The capacity of isolated GV oocytes to meiotic maturation in vitro decreased in the following order: estrus (75.