Means for producing embryonic stem (pES) cells which have a heterozygous genome that is matched to an individual donor are provided. In one embodiment, a means for the generation and isolation of parthenogenetic embryonic stem (pES) cells which have regions of heterozygosity that are fully matched to the oocyte donor at the MHC loci (e.g. (h-)p(MI)ES cells is provided. This is in contrast to the traditional methods of parthenogenesis that generate parthenogenetic embryonic stem (pES) cells having a substantially homozygous haploidentical set of chromosomes that are homozygous at the MHC loci.