Human trophectoderm becomes multi-layered by internalization at the polar region

The human blastocyst is composed of outer trophectoderm and an inner cell mass, which segregates into epiblast and hypoblast. scRNA sequencing of human blastocyst cells was performed to identify subpopulations following immunosurgery to remove outer cells. Donated human embryos from IVF clinics were subjected to immunosurgery and surviving cells were analysed by single cell sequencing