Practice question

The stem cell niche concept introduced by Schofield defines a specific anatomic and biochemical compartment that anchors stem cells and controls their behavior. It comprises supporting stromal cells, extracellular matrix, blood vessels, neural inputs, soluble factors like Wnt, BMP, Notch ligands, oxygen tension, and adhesion molecules. Niche signals suppress differentiation, regulate symmetric versus asymmetric division, and protect genome integrity. Disruption leads to stem cell loss or tumorigenic hyperplasia. Examples include intestinal crypt base, hair follicle bulge, and bone marrow endosteal zone, illustrating how location dictates fate.