Wound healing in the sex skin of pig-tailed macaques.

We studied wound healing in methacrylate- and araldite-embedded sex skin, a unique tissue that embodies the properties of friction surface and hairy skin. The largely light-microscopic observations were supplemented with transmission electron microscopy. The time of epidermal bridging was directly dependent on how closely apposed were the wound margins. Repair in the dermis always occurred more rapidly in the upper and in the lower parts of the wound gap than in the middle. Early in healing, the original epidermis cut off a wedge of skin in the upper wound margin (precocious remodeling) and cast it off at the margin of the clot. Remodeling (collagen resorption) inside the wound gap is accomplished primarily by fibroclasts. All mast cells in the vicinity of the wound attain fatty vacuoles. Adipose tissue near the wound undergoes lipolysis: the adipocytes gradually become smaller and their cytoplasm reticulated as small fat vesicles are extruded in the interstitium; fibroblasts, macrophages, polymorphonuclear leukocytes (PMNs) and mast cells readily phagocytose the fat vesicles. Elastic fibers do not participate in wound healing. There was no evidence of elastic fiber formation in granulation tissue.