[Foreign body giant cells: ultrastructure, cytochemistry, origin].

While analysing literature and our own data, it has been stated that the foreign body giant cells (FBGC) are viable elements possessing a high degree of metabolism. They have some specific ultrastructural features by which they differ from other elements (fibroblasts, macrophages) in an inflammatory focus. The FBGC of the inflammatory focus are formed from cells of the bone marrow origin. Cell-precursors of the FBGC intensively multiply outside the inflammatory focus and then migrate into it where processes of differentiation come to an end. Young FBGC can be formed by means of nuclear division. But the leading mechanism in the FBGC formation and in increasing the number of their nuclei is the process of cell fusion.