Electron Microscopic Detection of DNA Damage Labeled by TUNEL

A number of exogenous and endogenous toxic agents may damage DNA, leading to genomic instability and transcriptional infidelity. Genetic or acquired defects in DNA repair mechanisms also contribute to exacerbate DNA damage. Progressive accumulation of DNA injury may alter the genetic control of cell proliferation and cause cancer. Alternatively, increased cell death may be a more likely consequence if DNA damage affects postmitotic cells, e.g., neurons (1 ). As a matter of fact, DNA damage is suspected to play a major role in the neuronal death that characterizes brain ischemia (2 ) and various neurodegenerative diseases (1 ,3 ).