REVIEW Mechanisms of wound repair in crayfish

This review describes the complexity of events involved with repair to integumentary wounds and their regulation using the crayfish as a model system. Injuries to integument precipitate a cascade of cellular events that lead to rapid healing of the wound, regeneration of damaged tissues and repair of the integument. The first step in this cascade is hemolymph clotting and subsequent melanization, events documented thoroughly elsewhere and not discussed here. Wound healing and repair in crayfish involves the action of two physiological systems, the immune system and the neuroendocrine system regulating synthesis of the steroid molting hormones, ecdysteroids. Injury promotes a swift rise in hemolymph ecdysteroids to a low, sustained plateau, followed by a premolt peak and molting. The plateau is essential for wound healing since its principal targets are the circulating cells of the immune system, the hemocytes, and healthy epidermal cells and fibrocytes. Massive migration of these cells occurs under the wound and their concerted efforts under ecdysteroid control are paramount to wound healing and repair. These cells are likely engaged in physiological and biochemical activities that promote cell communication and cell to cell adhesion, removal of dead and harmful material and production of molecules essential to tissue regeneration. Key Words: Crustacea; immune system; ecdysteroids; hemocytes; epidermis; regeneratio