RNA and DNA synthesis of epidermal basal cells after wounding. Comparison of vital and postmortem investigations.

Incision wounds were made on both of the pinnae of each rat, and two biopsies from both the ears were taken for examination after different survival times of the wounds. Two biopsies were taken from each ear, four from each animal, two intravitally and two postmortem after 24 hours storage at 8 degrees C. One each of the intravital and one each of the postmortem biopsies were prepared and evaluated for quantification of RNA and DNA synthesis rate using an in vitro incorporation model with H-3-cytidine and bromodeoxyuridine (BrdU) as markers. The intravital specimens showed a significant increase in 3H-cytidine incorporation in the basal cell layer after survival times of 10 to 24 hours. No increase in the rate of RNA synthesis in the basal cell layer as a function of wound age was seen in postmortem specimens. In both intravital and postmortem biopsies the labelling indices after BrdU exposition increased significantly in the period from 32 to 60 hours post-injury. This suggest that DNA synthesis induced during life continues after death. Applied to forensic practice, these findings point to the possibility of determining the vitality of a wound in postmortem tissue. The RNA synthesis, obviously, precedes the DNA synthesis after mechanical trauma.