In-Vitro Culture of Rabbit Ova From Early Cleavage Stages to the Blastocyst Stage

Successful in-vitro culture of fertilized mammalian ova greatly facilitates the study of embryo development. Since Brachet (1912) reported culturing 5-day rabbit blastocysts, considerable effort has been devoted to the development of an in-vitro culture system for rabbit ova. Several investigators have reported culturing 1- and 2-celled rabbit ova to the morula stage, but not to the blastocyst stage (Lewis & Gregory, 1929; Smith, 1949; Chang, 1950; Purshottam & Pincus, 1961; Daniel, 1964; Edwards, 1964). The mouse ovum is obstinate in early cleavage stages, but Brinster (1963) recently has successfully cultured 2-celled ova to the hatched blastocyst stage. The peculiar difficulty for the rabbit ova may involve the presence of a relatively tough zona pellucida and mucin coat as pointed out by Pincus (1936). The present study was initiated to explore the possibility of in-vitro development of rabbit ova from predominantly 2- and 4-cell stages to the