The structure of metatarsal bones from 18-day-old rats subjected to intermittent mechanical force in organ culture are reported. The application of mechanical force enhances the osteoid thickness and osteoblast number in the periosteum and increases the number of viable osteocytes. These results indicate that (1) the mature bone tissue survives in organ cultures; (2) the mechanical forces better preserve the structure of the osteocytes and stimulate the osteoblasts, and (3) stimulate the osteogenesis.