Attempts to Produce Identical Offspring in the Sheep by Mechanical Division of the Ovum

Abstract

In an attempt to produce identical offspring artificially, the inner cell mass of ova, collected on days 4, 6 and 7 after oestrus (day 0 = day of oestrus), was mechanically divided into two equal sections. The sections were then either cultured in vitro for 2 days and the resulting apparently normal blasto-cysts transferred to recipient ewes or, in the case of day-7 ova, transferred to recipient ewes without a period of in vitro culture.