Practice question

Skin epidermis represents archetypal stratified continuously renewing tissue where basal keratinocytes attach firmly to collagen IV and laminin-rich basement membrane via hemidesmosomes and integrin alpha6beta4. This basal compartment houses Krt14-positive, p63-positive, slow-cycling stem cells that divide asymmetrically, generate transit-amplifying daughters, and differentiate upward forming spinous, granular, and cornified layers providing barrier. Mechanical tension and Wnt/BMP signals from underlying dermal fibroblasts regulate this highly organized niche. Cardiac muscle, mature neurons, and osteocytes are largely post-mitotic differentiated cells with minimal regenerative stem reserve, not examples of active regulatory niches sustaining self-renewal long-term.