Effects of luteinizing hormone and follicle stimulating hormone on the developmental competence of porcine preantral follicle oocytes grown in vitro.

There has been controversy over the role of FSH in the regulation of preantral follicle development. LH is a survival and differentiation factor that increases oocyte maturation in FSH-supplemented cultures of mouse preantral follicles. However, little information exists on the action of LH and FSH in the developmental competence of porcine preantral follicle oocytes in vitro. Porcine preantral follicles were cultured for 3 days in the presence or absence of FSH or LH. Oocytes from these follicles were then matured, fertilized in vitro, and embryos were cultured. Estradiol secretion and histological analysis of cultured follicles were also carried out. FSH or combined LH and FSH significantly enhanced follicular growth compared to LH alone or the controls. Combined LH and FSH treatment of preantral follicles significantly increased the percentage (59 +/- 5%) of oocytes competent to undergo cleavage to the two-cell stage after fertilization. A significant effect was seen on oocyte competence to develop from the two-cell to the blastocyst stage (30 +/- 6%) compared to FSH alone treatment (45 +/- 7 and 14 +/- 5%, respectively). The amount of estradiol on days 2 and 3 of culture was significantly higher in follicles cultured with FSH (48.75 +/- 17, 70.5 +/- 14 pg/ml) or combined LH and FSH (63.25 +/- 16, 72.5 +/- 12 pg/ml) than that cultured with the untreated controls (16 +/- 10, 5.66 +/- 4 pg/ml). The results indicated that FSH is essential for the in vitro growth of porcine preantral follicles, estradiol secretion, and for oocytes to acquire competence to resume meiosis and undergo fertilization and embryonic development. LH with FSH treatment of porcine preantral follicles can improve the quality of oocytes by promoting growth and a higher frequency of embryonic development.