Figure 2.

Wound closure is accomplished through different means in adult versus embryonic mice. A) The first stage of wound healing in adult mice is a hemostatic one, whereby the wound is closed with a fibrin clot. Damaged blood vessels lead to a coagulation of blood in the area of injury, activated platelets migrate to the site and form a sticky plug, and a fibrin network forms a mesh that ultimately creates a clot. B) In embryonic wounds, in lieu of a fibrin clot, at the leading edge of the wound epithelium, cells are connected to one another by actin filaments in a concentric circle around the wound. This cable acts as a contractile “purse string” that closes the wound without need of a coagulative cascade.