A histological study of the long-term response to trauma of squamate integument.

Scale neogenesis following excision of pieces of skin of various sizes and shapes has been studied in several squamate species. In small wounds, neogenesis does not occur, the wound region contracts, and increased areas of hinge differentiation are seen. In large wounds, the time taken for neogenesis to occur, and the size, shape, distribution, and number of the reformed units, are variable. We confirm previous reports that neogenesis accompanies a renewal phase of the shedding cycle, and suggests that this is because both types of morphogenesis require germinal stability. All types of trauma thus far studied show the initial formation of a hyperplastic wound epithelium with the histological characteristics of a normal α-layer: such tissues are the basis for physiological barrier functions. The mechanical functions of the skin can be fairly adequately restored even by abnormal neogenic scales. The observed variability in the process of scale neogenesis, and the final form of the individual units, are argued to be the result of mechanical factors impinging on the differentiating tissues.