[Infertility of the hamster oocyte having matured in vitro]

The comparative study of fertilization, with the same sperm sample, of in vitro matured oocytes and freshly ovulated ones, shows a new aspect of mammalian oocyte maturation. While 80% of freshly ovulated oocytes are fertilized, in vitro matured eggs are not fertilizable. They present the ability to be penetrated by spermatozoa 4 to 6 hrs. only after HCG injection. This is therefore not on tubal influence but depends on an oocyte specific factor which appears during the end of intrafollicular maturation.