MEIOTIC COMPETENCE OF PREPUBERTAL GOAT OOCYTES

The object of this work was to evaluate in vitro maturation of follicu lar oocytes from the ovaries of prepubertal goats obtained from the sl aughterhouse. To obtain the oocytes, follicles were dissected and clas sified according to their diameters. In the first experiment, oocytes were matured in vitro with granulosa cells. No significant differences were detected in the percentages of maturation between adult and prep ubertal goat oocytes recovered from follicles of 2.5 to 6.0 mm in diam eter (81.82 vs 72.47%, respectively). The percentage of maturation inc reased to 88.0% in prepubertal goat oocytes recovered from follicles o f 2.5 to 6.0 mm in diameter (81.82 vs 72.47%, respectively). The perce ntage of maturation increased to 88.0% in prepubertal goat oocytes fro m 3.0 to 6.0-mm follicles. In the second experiment, the percentage of maturation of prepubertal goat oocytes was greater after 27 than afte r 24 h. In the third experiment, the maturational capacity of prepuber tal goat oocytes according to follicular diameter was evaluated. The p ercentages of maturation after 27 h of culture with no granulosa cells were 24.14, 56.60 and 74.78%, respectively, for follicles 1.0 to 1.9 mm, 2.0 to 2.9 mm, and 3.0 to 6.0 mm in diameter. As the follicular di ameter increased, growth of the oocyte as well as a greater number of oocytes with more cumulus cell layers were observed. A correlation bet ween the diameter of the oocyte and its competence to complete in vitr o maturation was also observed. Oocytes with more cumulus cell layers showed only a slight superiority in their capacity for maturation in l arge-size follicles (3.0 to 6.0 mm), but the difference was not signif icant. In conclusion, oocytes from prepubertal goats complete their gr owth and reach meiotic competence in follicles larger than 3.0 mm. Wit h these oocytes it is possible to obtain in vitro maturation results s imilar to those from adult goats.