The Suppressive Effect of Sera from Old Female Mice on in vitro Fertilization and Blastocyst Development

Abstract

Superovulated, old and young female mice were either allowed to mate or were inseminated into the uterine lumen. Failure of mating occurred in the old but not in the young females. The average number of ovulations and proportion of fertilized eggs following insemination decreased significantly in the old rather than in the young females. It was found that for successful in vitro fertilization of mouse eggs, one culture medium was good for intact eggs and another one for denuded eggs, but both media were good for zona-free eggs. Treatment of unfertilized eggs and 8-celled eggs with sera of old females significantly reduced the rate of fertilization and the potential of development in culture, although treatment of zona-free eggs had no effect. Two out of 16 serum samples from old mice produced faint reaction on the zona pellucida of rat eggs by immunofluorescence test. It seems that factors which impair fertilization and early development are present in sera of old females and these factors may include an autoantibody to zona pellucida.