Late phase of fibroplastic stage of bone repair. Osteoclasts resorb necrotic bone. In areas of sufficient oxygen tension, osteoblasts lay down new bone; in areas of low oxygen tension, chondroblasts lay down cartilage. In addition, capillary ingrowth continues and internal and external calluses form. (Netter illustration from www.netterimages.com. © Elsevier Inc. All rights reserved