Fig. 2

Histological cross-section of the fractured rat femurs obtained 8 weeks after surgery. Group I showed partial cartilaginous tissue formation, but there was no evidence of fusion (a, b). Group II showed moderate new cartilaginous tissue formation and immature bone formation. Many of the observed chondrocyte cells exhibited expansion (c, d). Group III showed formation of contracted bone trabeculae. Although general mature bone formation had been observed, a moderate number of chondrocytes remained (e, f). Group IV exhibited well-developed bone trabeculae and bone marrow. Mature osteocytes were surrounded by bone marrow with increased cavity formation (g, h). In group V, abundant new bone tissue formed with the expansion of the bone marrow cavity. Although new bone tissue seemed to be mature compared with that of group II, immature chondrocytes remained (i, j). Group VI exhibited mature new bone formation with finely organized trabecular bone and multinuclear cells indicating osteoclasts, which implied bone remodeling (k, l)