Influence of oocyte quality, culture media and gonadotropins on cleavage rate and development of in vitro fertilized buffalo embryos

The present study was designed to examine the influence of oocyte quality, culture media and gonadotropins on cleavage rate and development of in vitr o fertilized buffalo embryos. Three experiments were conducted. In experime nt 1, oocytes were classified by number of cumulus cell layers and morpholo gy of the ooplasm as good, fair or poor. Oocytes were cultured for IVM, IVF and IVC in CR1aa medium. In experiment 2, good quality oocytes were cultur ed for maturation in: (1) CR1aa; (2) CR2aa; (3) TCM-199; (4) MEM or (5) R-P MI-1640, and then fertilized using frozen thawed buffalo spermatozoa in CR1 aa. The oocytes were cultured in the same medium used for maturation after fertilization. In experiment 3, oocytes were classified into three groups: group (1) was without gonadotropin and serve as a control; group (2) in whi ch IVM medium was supplemented with 10 mug/ml FSH and group (3) in which IV M medium was supplemented with 10 IU ml(-1) eCG. In all experiments, oocyte s were kept at 38.5 degreesC under 5% CO2 for IVM, IVF, IVC and examined fo r cleavage and embryo development rates on days 3 and 8, respectively. Good and fair quality oocytes produced a higher cleavage rate (P < 0.01) than p oor quality oocytes. Morula production rate was also higher (P < 0.01) for good as compared with fair quality oocytes. Embryo development with poor qu ality oocytes was arrested at the two to sixteen cell stage. In experiment 2, the cleavage rate was higher (P < 0.05) in CR1aa than CR2aa, and higher (P < 0.01) than TCM-199, MEM and RPMI-1640. The numbers of morulae and blas tocysts were higher (P < 0.01) for oocytes cultured in CR1aa and CR2aa medi a than TCM-199 or MEM. In experiment 3, the addition of FSH or eCG to the m aturation medium increased (P < 0.01) cleavage and developmental rates of b uffalo embryo compared with control medium. In conclusion, the IVM of good quality buffalo oocytes in CR I aa or CR2aa medium and the addition of FSH or eCG in maturation medium produced higher cleavage and developmental rate s of IVF buffalo embryos. (C) 2001 Published by Elsevier Science B.V.