Practice question

In mammals totipotency denotes ability to generate entire organism including both embryonic tissues and extraembryonic membranes like placenta. Zygote represents ultimate totipotent cell produced immediately after fertilization. Early cleavage blastomeres up to four to eight-cell stage retain this potential because lineage segregation, compaction and polarization have not yet occurred. After compaction outer cells activate Cdx2 and become trophoblast precursors while inner cells remain inner cell mass. Inner cell mass and embryonic stem cells derived from it are pluripotent, limited to embryonic lineages, not fully totipotent.