Fig. 4

The histology of red-eared slider turtle skin. Sections taken from the lateral and bed margins of the wound in insulin-treated and control turtles at 14 DPW. Insulin-treated wounds show abundant granulation tissue characterized by large fibroblasts (black arrows) disposed perpendicular (a, lateral margin) or parallel to the epidermis (c, wound bed); the BZM is well defined (a and c, blue arrows). Haematoxylin-eosin. Moderate quantity of collagen bundles (blue stained) are observed in the regenerate dermis (c, inset). Masson’s trichrome. At this time point, the granulation tissue (b, black arrow) and the BMZ (b, blue arrow) are less developed in control wounds and the inflammatory reaction more active (d, wound bed), characterized by oedema, heterophils and macrophages infiltration (arrows). Haematoxylin-eosin stain. At 21 DPW, the BMZ is better differentiated in insulin-treated wounds (e) than in control wounds (f) in which the epidermis was frequently detached (arrows)