Dev Cell 2017 06;41(6):581-589
The Azrieli Center for Stem Cells and Genetic Research, Department of Genetics, Silberman Institute of Life Sciences, The Hebrew University, Jerusalem 91904, Israel. Electronic address:
Although haploidy has not been observed in vertebrates, its natural occurrence in various eukaryotic species that had diverged from diploid ancestors suggests that there is an innate capacity for an organism to regain haploidy and that haploidy may confer evolutionary benefits. Haploid embryonic stem cells have been experimentally generated from mouse, rat, monkey, and humans. Haploidy results in major differences in cell size and gene expression levels while also affecting parental imprinting, X chromosome inactivation, and mitochondrial metabolism genes. We discuss here haploidy in evolution and the barriers to haploidy, in particular in the human context.