DNA interstrand crosslinks in normal human skin visualized by electron microscopy.

Normal human skin was investigated for DNA interstrand crosslinks by a denaturation electron microscopic method. Skin biopsy materials from the thighs of 8 healthy volunteers were separated into epidermis and dermis. DNA from each layer was isolated, purified and studied in the electron microscope. The presence of DNA interstrand crosslinks in normal human skin was demonstrated. The number of crosslinked DNA molecules and the density of crosslinking within the molecules were determined. Crosslinks were found in 0.8% of the scored molecules and were located almost exclusively in epidermal DNA. The intramolecular density of crosslinking showed a wide range of variation in each volunteer and between the volunteers.