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Apoptosis: Programmed Cell Death

Definition of Apoptosis

Apoptosis is cell death, controlled by gene expression, which includes, in contrast to necrosis, the avoidance of cytokine release or inflammation triggering.

Mechanisms of Apoptosis

• signal transduction (external or internal stimuli)
• Shrinkage of the cell
• Bubble-like protrusions at the cell surface
• Condensation and degradation of DNA
• Degradation of mitochondria
• Fragmentation of the cell into small membrane-bound fragments (apoptotic bodies)
• Exposure of the phospholipid phosphatidylserine on the surface of apoptotic bodies
• Phagocytosis of apoptotic bodies by macrophages

Significance of Apoptosis

Apoptosis (controlled cell death) is essential for normal development and body functions:

• Control of growth and size of tissues
• Control of embryogenesis
• Elimination of potentially harmful cells
• Selection of genetically intact germ cells
• Selection and reduction of unnecessary or potentially harmful cells of the immune system
• Disorders of apoptosis can lead to cancer or autoimmune diseases

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References

  Deutsche Version: Apoptose