X inactivation--the transcriptional silencing of one X chromosome copy per female somatic cell--is universal among therian mammals. yet the choice of which X to silence exhibits considerable variation among species. X inactivation strategies can range from strict paternally inherited X inactivation (PXI). which renders females haploid for all maternally inherited alleles. https://www.kvmrentals.com/product-category/line-friends/