Practice question

Developmental potency narrows progressively through epigenetic restriction and lineage priming. Zygote and early blastomeres up to two to four cell stage are totipotent, able to produce embryonic plus extraembryonic placenta and yolk sac membranes. Inner cell mass subsequently restricts to pluripotent state, generating ectoderm, mesoderm, endoderm but not trophoblast under normal conditions. Subsequently hematopoietic stem cells become multipotent within blood lineages only, and committed progenitors become unipotent forming one mature type such as erythrocyte or spermatogonium. This hierarchy underlies stepwise differentiation trajectories and transplantation potential.