Practice question

Schofield originally proposed the niche concept in 1978 to describe a specialized environmental unit that physically limits stem cell number and preserves phenotype. Molecularly, it comprises supporting stromal cells secreting BMP, Wnt, FGF, adhesion molecules like N-cadherin, oxygen tension modulators, and extracellular matrix providing mechanical cues through stiffness. Disruption of niche architecture leads to stem cell loss or tumorigenic over-proliferation due to loss of quiescence signals. Unlike generic storage sites, the niche actively instructs self-renewal versus differentiation balance through short-range juxtacrine and paracrine interactions governing regeneration and aging.