Maturation and in vitro Fertilization of Follicular Oocytes of the Squirrel Monkey (Saimiri sciureus)

Abstract

These studies were conducted to examine the procedures and variables of an in vitro fertilization system used to provide embryos for developmental studies in the squirrel monkey, Saimuri sciureus. During these trials, conducted over the past 5 years, 745 oocytes were aspirated from 2168 follicles (34.4% recovery rate). Of these oocytes 137 (18.4%) were atretic. Of the remaining 608 oocytes, 38% matured to the metaphase II stage. Differences in aspiration procedures did not affect maturation or in vitro fertility. Male squirrel monkeys used to supply semen were of significantly differing fertility. Volumes and cellular composition of follicular fluid were determined for 4 sizes of follicles and of these the smallest (1 mm diameter) follicles yielded significantly higher proportions of atretic ova. The highest in vitro fertilization rates occurred with 5% CO2 in air with a TC-199 medium containing both pyruvate and serum proteins. Addition of either 10 or 100 mIU of insulin to this culture medium did not alter in vitro maturation or fertilization, but did significantly reduce the formation of monolayers by follicle cells.