Wound Healing

• new epithelium grows over the healing wound, stimulated by PDGF made by platelets and macrophages. not all tissues need new epithelium

• new blood vessels grow into the tissue at the same time that fibroblasts do. this mixture of cells is called granulation tissue. this process also causes the wound to contract, but you don’t have to let it contract if you suture the wound together. sometimes, you don’t even want the wound to contract in a location like the elbow, where articulation is necessary. an epithelial graft won’t prevent wound contraction and will eventually lead to a stiff elbow, but a full thickness graft will prevent wound contraction (as long as the graft is not rejected)

• some tissues, such as the liver, can grow new, functional cells

• other tissues, such as the heart and brain, do not regrow. dead heart muscle makes a fibrous scar. this may change with stem cell research

Category: Pathology Notes