Labile

Cells are classified by replicative potential as labile, stable, or permanent. Labile cells are in active cell cycle (never enter G0) and include surface epithelia (skin, oral cavity, GI tract, cervix, vagina), hematopoietic precursors in marrow, and germ cells. Because they regenerate constantly, they are especially susceptible to cytotoxic injury (chemotherapy, radiation) causing alopecia, mucositis, and cytopenias. They are contrasted with stable cells (G0, can re-enter cycle, e.g., hepatocytes, proximal tubule, fibroblasts) and permanent cells (cannot regenerate, e.g., neurons, cardiac and skeletal muscle). Knowing this classification predicts what tissues scar versus regenerate after injury.