HISTOLOGICAL CHARACTERISTICS OF THE HEALING-PROCESS OF FROZEN SKIN ALLOGRAFT USED IN THE TREATMENT OF BURNS

Combined transplantation of skin autograft and allograft was used for the treatment of severe burns. The allografts were obtained from cadav ers and were pretreated with 15 per cent glycerol for 2 h at 4 degrees C then frozen at -80 degrees C until used. Patches of autografts were placed over the barns and were covered by a stretched mesh of allogra fts. Biopsy samples of transplanted skin were obtained from 5 days to 4 weeks offer grafting, Sections were examined by histological and imm unohistochemical strainings. At 4 days, the epidermal-dermal junction of allografted skin was separated due to migration of epithelial cells derived from autograft epidermis or from skin appendages of recipient dermis. At 2 weeks, dermal fibroblasts and capillaries proliferated i n autografts. At 3 weeks, the dermal components of the allograft were covered by epithelial cells from recipient tissue and were invaded by fibroblasts and capillaries. At 4 weeks, allografted skin was replaced by granulation tissue, which mediated the adhesion of the grafts to t he underlying tissue. Skin allografts with a freeze-thawing pretreatme nt provide an appropriate matrix for the epithelial relining and for t he growth of granulation tissue in burned skin.