Maturation and Fertilization in Vitro of Guinea-Pig Ovarian Oocytes

Mammalian ovarian oocytes can mature in vitro when liberated from Graafian follicles and placed in appropriate culture media. This was first demonstrated in the rabbit (Pincus & Enzmann, 1935, 1937; Chang, 1955a, b) and has been confirmed in a variety of animals (see Donahue, 1972; Biggers, 1973; Fowler & Edwards, 1973). According to Jagiello (1969), 80 to 100% of guinea-pig oocytes isolated from ovaries of adult females in the middle (Days 5 to 8) of their oestrous cycle resume meiosis upon culture and may reach metaphase II by 14 hr of culture. Unfortunately, Jagiello gave no detailed information of the techniques which she used for isolation and culture of the oocytes and did not determine whether the oocytes matured in vitro were fertilizable. This paper describes a method of culturing