Fertilization potential of follicular oocytes classified by stage of cycle and size of follicle.

Bovine follicular oocytes, collected from two sizes of vesicular follicles and from donor animals from three stages of the estrous cycle, were matured and fertilized in vitro. Frequency of fertilization and ability to form male pronuclei after in vitro maturation were found to be independent of both estrual stage and follicular size.