In vitro culture of goat preantral follicles from fetal ovaries

The objective of the present study was to investigate the influence of thyroxin (T4), follicle stimulating hormone (FSH), growth hormone (GH), epidermal growth factor (EGF) and insulin like growth factor-I (IGF-I) individually or in combination on in vitro development of goat fetal preantral follicles (PFs). PFs (100-300 μm) were isolated from the fetal ovaries of more than 125 days of gestation and cultured for a period of 6 days. The development of the cultured PFs was assessed by the proportions of follicles exhibiting growth, increase in diameter, antrum formation, and extrusion of oocytes in vitro, if any. In the first experiment, PFs were cultured in tissue culture medium 199 supplemented with different individual concentrations of T4 (0.5, 1 and 2 μg/mL), FSH (1, 2 and 4 μg/mL), GH (1, 2 and 4 mIU/mL), EGF (10, 25 and 50 ng/mL) and IGF-I (10, 15 and 20 ng/mL). The proportion of PFs exhibiting growth, increase in diameter and antrum formation were highest when the PFs were cultured at T4:1 μg/mL, FSH:2 μg/mL, GH:1 mIU/mL, EGF:25 ng/mL or IGF-I:10 ng/mL. Among the different individual concentrations of growth factors and hormones, the extrusions of oocytes from cultured PFs were observed only in GH and EGF supplemented media. In the second experiment, the effect of different combinations of the above and hormones and growth factors at their best concentrations as determined in the first experiment was investigated. The average increase in diameter (50.56 ± 3.8 μm), the proportion of PFs exhibiting antrum formation (96.54 ± 2.4) and extrusion of oocytes (25.79 ± 1.8) were highest when cultured in T4 + FSH + GH + EGF supplemented medium. However, the proportion of extrusion of oocytes was similar in T4 + FSH + IGF-I, T4 + FSH + GH + IGF-I and T4 + FSH + EGF + IGF-I combinations. In conclusion, the in vitro development of goat fetal PFs could be significantly improved when the medium was supplemented with T4 + FSH + GH + EGF.