Preimplantation development of gynogenetic diploid mouse embryos

Diploid gynogenetic mouse embryos were produced in a three-step procedure: fertilization in vitro, suppression of the 2nd polar body formation by Cytochalasin B, and microsurgical removal of the male pronucleus. The operated eggs were transplanted to the oviduct of recipient females for 72 or 96 h. The overall recovery rate was 73%, but compacted morulae and blastocysts constituted only 28.6% of transplanted eggs. After 72 h blastocysts were rare (3.5%) but 24 h later their incidence increased to 21.2%. In eggs homozygous for T6 chromosome it was possible to prove karyologically that the male pronucleus was effectively removed and that the diploid genome was of purely maternal origin.