Practice question

Induced pluripotent stem cells are artificially created in laboratory by delivering defined pluripotency-associated factors into differentiated somatic cells such as dermal fibroblasts, triggering extensive epigenetic reprogramming and transcriptional reset, not occurring spontaneously during normal embryogenesis or adult homeostasis. In vivo pluripotent cells are restricted to transient inner cell mass and epiblast stages before gastrulation. iPSCs require viral or non-viral genetic manipulation, mesenchymal-to-epithelial transition intermediate, and selection for reactivated endogenous pluripotency markers. Misconstruing them as naturally present in embryos confuses engineered models with endogenous developmental states and distinct regulatory logic involved.