IN-VITRO MATURATION OF HORSE OOCYTES

Ovaries collected from slaughtered mares of unknown reproductive histo ry were transported to the laboratory, and their oocytes were recovere d and cultured in modified TCM 199 supplemented with 20 % horse serum and additional granulosa cells. To characterize the ovaries, the size and number of follicles were counted. To determine the time required f or nuclear maturation, oocytes were fixed either after 18 h (n=23), 24 h (n=50), or 30 h (n=33) of culture. After co-culture with granulosa cells most oocytes reached metaphase II (M II) by 30 h (72.7 %). After 24 h of maturation only 56.0 % of the cultured oocytes had reached me taphase II (M II).