DEVELOPMENT OF HAMSTER EGGS FERTILIZED IN VITROOR IN VIVO

Although many workers have fertilized hamster eggs in vitrosince the technique was first described by Yanagimachi & Chang (1963), there is only one reported attempt to obtain further development of these eggs in culture (Yanagimachi & Chang, 1964). In this instance, development ceased at the two-cell stage. The present study examines the development in culture of hamster eggs fertilized in vitroand after transfer to recipient foster mothers.Immature female hamsters (5 to 6 weeks old and 60 to 80 g in weight) were induced to superovulate with intraperitoneal injections of 25 i.u. PMSG and HCG given 48 to 56 hr apart. Following removal of the oviducts 15 to 17 hr after the injection of HCG, they were blotted on sterile filter paper to remove excess blood and immersed in liquid paraffin contained in a Petri dish (35 mm in diameter, Falcon Plastics). The eggs and surrounding cumulus cells