MATURATION, TRANSPLANTATION AND FERTILIZATION OF OVARIAN OOCYTES IN CATTLE

Abstract

Cytological examination of the oocytes of a number of mammalian species has indicated that they will resume meiosis upon liberation from the Graafian follicle into a simple culture medium (Chang, 1955; Edwards, 1962, 1965a, b). Evaluation of the physiological status of such oocytes after periods of maturation would best be tested by noting their ability to undergo fertilization, cleavage and, ultimately, to produce viable young. Recent experiments have attempted in-vitro fertilization of mammalian eggs matured in culture and, whilst this has apparently yielded some success with human material (Edwards, Bavister & Steptoe, 1969) and in the rabbit (Thibault & Gérard, 1970), the contrary has proved the case in the large domestic species. In many experiments involving cow and pig eggs, sperm penetration of the zona pellucida of artificially matured oocytes was never