Apoptosis, or programmed cell death, plays a fundamental role in many biological processes such as morphogenesis and negative selection in the immune system, as well as in multiple disease states such as cancer and neurodegenerative diseases. Apoptotic cells can be recognized by a characteristic pattern of morphological, biochemical and molecular changes.
Starting materials include: formalin fixed (wet tissue), frozen tissue in OCT, paraffin block, or slide.
Morphological changes:
Loss of cell surface structures- Cell shrinkage and shape change
- Condensation of cytoplasm and nuclei
- Nuclear envelope changes
- Nuclear fragmentation
- Apoptotic body formation
Biochemical changes:
Free calcium ion rise- bcl2/BAX interaction
- Cell dehydration
- Loss of mitochondrial membrane potential
- Proteolysis
- Phosphatidylserine externalization
- DNA denaturation
- 50-300kb endonucleolytic cleavage of chromatin
- Protein cross-linking