A convenient source of fertilized ova at the appropriate stage of development is a prerequisite for successful ovum transfer. Since it has not yet been possible to fertilize freshly ovulated, or even follicular oocytes, which have been obtained from slaughter-house material, in vitro, or after transfer to inseminated sows in vivo, the only remaining sources of fertilized eggs are from naturally or artificially inseminated sows during the first days following ovulation. In particular, if the technique of simultaneous, reciprocal egg transfer between individuals is to be employed, it is important to recover the ova from the living animal. Judicious planning of transfer experiments necessitates the recovery of a maximal proportion of the ovulated eggs in a cleaved stage.
Hitherto, only a few experiments on the in-vivo recovery of swine ova have been described. Schmidt &