Development of early mouse and rabbit embryos without zona pellucida

: Criteria for assessing embryo vitality of denuded rabbit and mouse embryos in vitro were: volume of the embryo, number of cells and number of metaphase plates after 24 and 48 h in culture. Mouse embryos grew normally, with and without the zona pellucida, but denuded rabbit embryos showed reduced growth (volume and cell number) and failure to implant in synchronized recipients.