The vascular mantles of labyrinthine bone; a comparative anatomical study.

The vascular mantles of the endochondral layer of labyrinthine bone in dog (Canis f. intermedius Woldrich) and monkey (Pithecus fascicularis Raffl.) were examined by means of light and transmission electron microscopy and compared to those in man. A three-dimensional reconstruction of vessels and their vascular mantles is demonstrated. It is shown that these mantles only cover parts of the vessel. Using polarized light one can find vascular mantles containing lamellar fragments. By means of transmission electron microscopy a canalization of perivascular mantle matrix can be demonstrated. The ultrastructure of cells in mantle zones shows that these cells are osteoblasts, osteocytes, and osteoclasts. Signs of osteocytolysis are found. The importance of oxygenation via canalization of the vascular mantle matrix is discussed as well as the importance of lacking biomechanical stress in endochondral layer as to their influence on formation of vascular mantles. According to the "embryologic character" of endochondral layer an analogy between incomplete osteons which are to be found in developing woven bone and vascular mantles is considered.