Use of fetal bovine serum substitutes for the protection of the mouse zona pellucida against hardening during cryoprotectant addition.

Abstract

The addition of 20% fetal bovine serum (FBS) to media used for mouse oocyte cryopreservation prevents hardening of the zona pellucida that otherwise can occur due to premature release of cortical granule contents (George et al., Hum. Reprod., 7, 401-412, 1992). Protection of human oocytes would ideally be achieved by using a human macromolecular source or a more defined bovine source than total FBS. Here we investigate whether FBS can be replaced by human serum, human cord serum, human serum albumin or fetuin, the major protein component of FBS. Only fetuin was found to be effective.