Transmission electron microscopy of bone tissue: A review

Remodeling permits the bone to preserve its static and dynamic functions. If this process is disturbed the bone becomes more susceptible to fracture. Remodeling also allows the bone to play a major role as a bank of mineral substances, mainly calcium and phosphorus. The remodeling activities, a very precise sequence of events, concerns compact bone tissue of cortices, as well as cancellous bone tissue. After activation, leading to the birth of osteoclasts from hemopoietic stem cells, there is an osteoclastic resorption forming Howship lacunae. Then, and following a reversal phase, osteoblasts come from osteoprogenitor cells and rebuild bone tissue during the formation phase. There is a coupling, in space and time, between resorption and formation activities (Frost 1973). The purpose of this paper is to review the transmission electron microscopy aspects of bone tissue in order to evaluate (a) the composition of calcified and not yet calcified matrix, (b) the structure and role of osteoclasts and osteoblasts, (c) the aspects of bone cells not directly involved in bone remodeling, such as osteocytes and lining cells.