Practice question

Population asymmetry describes a tissue-level strategy for stem cell maintenance where balanced output emerges from the population, not from every single division. Individual stem cells may divide symmetrically producing two stem cells or two differentiating daughters, or asymmetrically producing one of each. Across the niche, stochastic choices average to maintain constant stem cell numbers while supplying differentiated cells. This contrasts with invariant single-cell asymmetry where each division is strictly asymmetric. Intestinal crypts and epidermal basal layer demonstrate population asymmetry regulated by Wnt and niche signals, ensuring robust homeostasis despite random individual fates.