During interphase the chromatids duplicate themselves by an exact replication, when DNA has to be synthesized. Apoptosis The orderly or programmed death of cells is needed to balance cell proliferation in mature renewing tissues, such as blood and epithelia. Also, one strategy of development is to overproduce cells, then select, e.g., for the survival of correctly connected neurons, or of lymphocytes reactive to non-self antigens. Thirdly, if an organ can not work properly, e.g., a gland has a blocked main duct, or its hormonal drive stops, many cells die by apoptosis. For apoptosis, endonucleases are activated which break up the chromatin, chopping up the DNA, transcription slows and stops, organelles clump, and the GER dilates.
Caspases digest relevant cellular materials and structures.
The cell and internal membranes bleb out. Apoptosis is intentionally unobtrusive, to remove single cells without provoking inflammation or upsetting tissue function. Quite often, the inclination of cells is to die, and they need signals not to undergo apoptosis. Stem cells For a stable population, the corollary to cell death is cell renewal . More is known about the ensuing progenitor cells than about the stem cells.