Establishment of pluripotential cell lines from haploid mouse embryos

Eggs from 129 SvE and (C57BL × CBA)F1 hybrid female mice were activated parthenogene tically following their exposure to a 7% solution of ethanol in PBS. Only the haploid cla ss which developed a single pronucleus following second polar body extrusion was examined further. These eggs were transferred to suitable recipients and ‘delayed’ blastocysts subsequently recovered. The ‘delayed’ blastocysts were explanted into tissue culture and a total of four haploid-derived pluripotent cell lines established from individual embryos. Chromosome analysis of morulae revealed that over 80% contained only haploid mitoses. However, chromosome analysis of early passage cell lines revealed that all were diploid with a modal number of 40 chromosomes. When transplanted into syngeneic hosts, all lines formed well-differentiated teratocarcinomas. This technique provides a source of homozygous diploid cell lines of parthenogenetic origin.