Cell specialization links selective gene expression, stem cell potency, cell size, exchange surfaces, and specialized tissues to biological function in multicellular organisms.
Coverage 2010–2025 · Updated 15 Jul 2026
• A zygote divides to produce unspecialized cells that later differentiate
• Differentiation occurs when different genes are activated in different cells
• Morphogen gradients control gene expression and body pattern formation
• Stem cells self-renew by repeated division while remaining undifferentiated
• Stem cells have potency: the capacity to differentiate into mature cell types
• Embryonic stem cells have broader potential than most adult stem cells
• Stem cell niches provide signals that maintain, activate, or differentiate stem cells
• Bone marrow niches regulate haematopoietic stem cells that form blood cells
• Hair follicle bulge niches contain multipotent stem cells for hair regeneration
• Totipotent cells can form all body cells plus placental cells
• Pluripotent cells form all body cell types but not placenta or totipotent cells
• Multipotent adult stem cells repair and maintain limited tissues or organs
• Specialized cells vary widely in size according to function
• Egg cells are large for nutrient storage; sperm are small with a long flagellum
• Neurons can be very long, and striated muscle fibres are extended multinucleate cells
• Surface area controls exchange, while volume controls metabolic demand
• As cells grow, volume increases faster than surface area
• Low surface area-to-volume ratio limits diffusion and therefore cell size
