Practice question

Stem cell definition unites two functional properties: prolonged self-renewal via symmetric or asymmetric divisions maintaining undifferentiated pool and differentiation potential generating specialized progeny of tissue. Self-renewal driven by telomerase, Bmi1 polycomb and niche signals Wnt, Kit ligand, Notch preserves genome replication preventing exhaustion. Multilineage differentiation regulated by lineage transcription factors like PU.1 for myeloid or Neurog3 for endocrine pancreas. Single division then terminal differentiation describes transit amplifying progenitor, always symmetric division inaccurate description, lacks potency inaccurate. Therefore stemness defined by balanced self-renewal and potency producing tissue homeostasis, repair and regeneration throughout organism lifespan and development.