Effects of oocyte quality, maturation media and gonadotropins on in vitro maturation of buffalo oocyte.

摘要

This study was carried out to investigate the effect of oocyte quality and different culture media as well as hormones on in vitro maturation of buffalo oocytes. 1197 oocytes were collected from 591 ovaries obtained from a slaughterhouse. The number of follicles on the ovarian surface was counted and the number of follicles/ovary was calculated. Oocytes were aspirated and the number of recovered oocytes per ovary was calculated. The recovery rate was determined. Oocytes were classified according to the appearance of cumulus cells into excellent, good, fair and poor. They were cultured either in TCM-199 or mSOF with different hormonal supplements (FSH, hCG or combination of both) for 24 h in CO< sub>2 incubator at 38 degrees C. Assessment of maturation by cumulus cell expansion and nuclear maturation was carried out. It was shown that 174 out of 258 excellent oocytes reached G3 with a percentage of 67.4%, 143 out of 249 good oocytes reached G3 with 57.4% and 146 out of 309 fair oocytes reached G3 with 47.2%, while all 280 poor (denuded) oocytes did not reach G3. Excellent oocytes exhibited higher significant (P<0.01) value than the other qualities. The percentage of nuclear maturation of excellent and good oocytes were 83.9 and 75.6%, while that of fair and poor oocytes were 71.8 and 59.5%, respectively. The maturation rate for excellent quality oocytes was significantly (P<0.01) higher than the other qualities. Buffalo oocytes that reached G3 of cumulus cell expansion in case of FSH addition were 55.7 and 39% for mSOF and TCM-199, while in the case of FSH + hCG addition the ratios were 57.8 and 26.7%, respectively. The differences were highly significant (P<0.01). Concerning nuclear maturation, TCM-199 exhibited a significantly higher (P<0.01) maturation rate than mSOF medium using FSH hormone (74.2 and 67.5%, respectively). There was no significant difference of maturation rate between TCM-199 and mSOF media using FSH plus hCG. Concerning the effect of hormones on buffalo oocytes, the study revealed that FSH gave higher (P<0.05) G3 cumulus cell expansion (39%) than hCG (32.4%) and FSH + hCG (26%) in case of TCM-199 medium. No significant differences were observed between hormonal treatments in the case of mSOF medium. FSH + hCG treatment gave higher (P<0.01) nuclear maturation rate (79.5%) than FSH (74.2%) and hCG (62.9%) in TCM-199 medium. Parallel results were observed in the case of mSOF medium. In conclusion, mSOF enhances cumulus expansion more than TCM-199, while TCM-199 enhances nuclear maturation of buffalo oocytes than mSOF. FSH + hCG is the best combination of gonadotropins that enhance both cumulus expansion and nuclear maturation rate of buffalo oocytes.