Apoptosis means: September 2005: (A) Regeneration of cells after injury, (B) Reperfusion injury of the cells, (C) Programmed internal cell death, (D) Uncontrolled multiplication of cells
Answer is C. Ans. C: Programmed internal cell death Apoptosis is defined as a process of programmed cell death (PCD) that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes include blebbing, loss of cell membrane asymmetry and attachment, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation. Apoptosis differs from necrosis, in which the cellular debris can damage the organism. Apoptosis in physiological conditions: - During embryogenesis - Involution of hormone-dependent tissues upon hormone withdrawl, such as endometrial cell breakdown during menstrual cycle, ovarian follicular atresia in menopause etc. - Cell loss in proliferating cell populations, such as immature lymphocytes in the bone marrow. Elimination of potentially harmful self-reactive lymphocytes