Healing of cutaneous wounds in the common garter snake (Thamnophis sirtalis)

Healing of cutaneous wounds was studied in groups of common garter snakes (Thamnophis sirtalis) held at 13.5 degrees C, 21 degrees C and 30 degrees C. Linear unsutured incisions and circular excisional wounds were evaluated two, five, and ten days after surgery, while linear sutured and unsutured incisions and circular and square excisional wounds were studied three and six weeks after wound production. The sequence of events during healing was the same for all experimental situations. The epithelial margins of the wounds moved freely over exposed epaxial muscle until an exudate of fibrin and inflammatory cells caused adhesion. Heterophils and macrophages were present two days after wounding. Heterophils were present throughout the wound while macrophages were concentrated in areas containing fibrin and proteinaceous exudate. Fibroblasts moved laterally into the wound from the adjacent dermis producing a flat dermal scar oriented parallel to the wound surface. Epithelial cell hypertrophy and hyperplasia occurred in a zone extending up to 1.5 mm from the margin of the wound. A tongue of flattened epithelial cells extended across the wound surface, mingling with the superficial crust and migrating over eosinophilic fibrillar material. Maturation of the new epithelium, indicated by formation of a distinct basal layer, rounding of superficial cells and keratin production, began at the wound margins before the epithelial spurs linked. The epithelium over healed wounds appeared normal, but the dermis did not reorganize to form scales. Reptilian and mammalian healing differ in the character of the inflammatory reaction, the pattern of fibroplasia, and the interaction between epithelial and dermal repair.