| Abstract: | Hypophysectomy of 15-day-old rats (hypox) markedly reduced the normal development of meiotic competence and abolished the development of antral follicles between days 21 and 31 postpartum (pp). Here the correlation among age of the rats, stage of follicular development, and meiotic competence was examined. Administration of pregnant mare's serum gonadotropin (PMSG-3IU) or insertion of an estradiol-17β (E2) capsule to hypox rats induced the development of meiotic competence provided the treatment started after day 20 pp. Hormonal treatments at an earlier age were not effective in inducing meiotic competence in hypox rats. The induction of meiotic competence by PMSG or E2 was associated with an increase in the number of granulosa cells and formation of follicular antrum. The finding that PMSG and E2 failed to induce meiotic competence when administered prior to day 21 pp suggests that the development of meiotic competence is an age-dependent process. When the hormonal treatments commenced after day 21, both follicular development and meiotic competence were induced. |
