An autoradiographic study of mucopolysaccharide and phosphate complexes in bone growth and repair.

The experimental study of bone growth and repair began with Belchier’s observation in 1736 of the staining with madder root of bones in vito. This technique was used by such men as Duhamel and John Hunter, and, with the development of the microscope, morphological studies on bone were carried out by Goodsir, Oilier, Macewen and many others (Keith 1919). A more recent review of these and of later experimental investigations was made by Bertelsen in 1944. More speciaiised techniques and methods, such as Fell’s (1925) in vitro tissue culture technique and the in vivo anterior eye transplantation method of Urist and McLean (1952), have provided much information about the origin and function of the principal cellular components of bone. However, this is still a controversial matter, and, although the histological process of endochondral ossification, growth and repair is well recognised, there is still much uncertainty and lack of knowledge of the histochemical aspect. The true histochemical study of bone growth and repair began with the development of new and specific staining methods (Lison 1936, Gomori 1939), and these have been much used in the past few years (Wislocki et al. 1947, Pritchard and Ruzicka 1950). Bone is composed of osteogenic cells and an intercellular substance consisting chiefly of collagen which may be suiphonated (Ham 1953). Between the fibrils of collagen there is a deposition of mineral salts in the form of crystals of hydroxyapatite (Robinson I 952) which is of the nature of tricalcium phosphate hydrate with salts of calcium carbonate and magnesium in the surrounding amorphous cement substances (Hendricks and Hill 1951). Sylv#{233}n (1947) renewed interest in the metabolism of chondroitin sulphuric acid in cartilage, and more recently Foilis (1952) described cartilage as consisting of collagen, a mucopolysaccharide-chondroitin sulphuric acid-and lipoid material with minerals. A mucopolysaccharide is considered to be a hexosamine-containing carbohydrate or polysaccharide which may or may not be combined with a protein (Pine 1946). In the group in which the carbohydrate is combined with a protein, as well as chondroitin sulphuric acid there are hyaluronic acid, mucoitin-suiphuric acid and heparin. The original concept of Robison and Rosenheim (1934) that the enzyme alkaline phosphatase was concerned with calcification by increasing the local concentration of inorganic phosphate has been broadened. The enzyme is now considered to be closely concerned with pre-osseous cellular metabolism, with subsequent elaboration of a bone matrix and resulting precipitation of calcium and phosphate ions (Siffert 1951). However, since the histological change from cartilage to bone is accompanied by a biochemical change from mucopolysaccharides to calcium phosphate complexes, this can be studied in vivo by the use of suitable radioactive isotopes. Various earlier workers have described the distribution, metabolism and excretion of radioactive sulphur (35S) and phosphorus (32P) in bone. In particular, Dziewiatkowski (1951, 1952, 1953) has shown by autoradiography that 35S is incorporated in sections of articular cartilage and other organs of the rat, and he relates its uptake to the mucopolysaccharide chondroitin sulphuric acid. Bostr#{246}m (1952, 1953) confirmed and demonstrated this observation quantitatively, and has shown how the fixation of this isotope is dependent upon an enzyme system which is influenced by temperature, by oxygen pressure, and by drugs such as cortisone