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 b iopsies from both the ears were taken for examination after different survival times of the wounds. Two biopsies were taken from each ear, f our from each animal, two intravitally and two postmortem after 24 hou rs 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 w ith H-3-cytidine and bromodeoxyuridine (BrdU) as markers. The intravit al specimens showed a significant increase in 3H-cytidine incorporatio n in the basal cell layer after survival times of 10 to 24 hours. No i ncrease in the rate of RNA synthesis in the basal cell layer as a func tion of wound age was seen in postmortem specimens. In both intravital and postmortem biopsies the labelling indices after BrdU exposition i ncreased significantly in the period from 32 to 60 hours post-injury. This suggest that DNA synthesis induced during life continues after de ath. Applied to forensic practice, these findings point to the possibi lity of determining the vitality of a wound in postmortem tissue. The RNA synthesis, obviously, precedes the DNA synthesis after mechanical trauma.