ELECTRON-IRRADIATION SLOWS DOWN WOUND REPAIR IN RAT SKIN - A MORPHOLOGICAL INVESTIGATION

To date, there have been few morphological investigations of the effec t of electron radiation on the healing of skin wounds in rats. The pre sent morphological study examines the wound repair process in electron -irradiated rat skin by electron microscopy. Standardized, full-thickn ess, incisional wounds were made in the lower dorsal skin of animals w hich had been locally irradiated with 9.6 Gy electron radiation 7 days previously. The irradiation dose was maximal at 3 mm depth. Twenty-fo ur rats were used in the investigation; 12 were irradiated and 12 sham -irradiated. Three rats from each experimental group were killed at 1, 3, 7 and 14-day time intervals after wounding. The morphological effe ct of electron irradiation on the repair of each wound was investigate d by light microscopy (LM) and scanning electron microscopy (SEM). New granulation tissue visualized by SEM was quantified using computerize d image analysis. The results suggest that a single, partial-body, con trolled depth dose of electron irradiation delays wound repair. LM sho wed that there is a depression of the inflammatory cell and tissue exu date response, slowing of epithelial migration, and a decrease in fibr oblast representation, together with a delay in the formation of colla gen bundles. Granulation tissue formation was impaired up to 7 days po st-wounding, but was restored to around control values by day 14, indi cating that healing was delayed. However, as the healing of normal tis sue was not prevented, this study supports a preoperative role for the use of low-dose electron irradiation therapy for the treatment of ele ctron-sensitive superficial pathologies in surgical practice.