An electron microscopic examination for the presence of acid groups in the organic matrix of mineralization nodules in foetal bone.

Several biochemical and histochemical investigations of the role of glycosaminoglycans (GAG) in bone and cartilage mineralization have been performed, but the exact relationship between GAG and mineralization is not clear. We performed an electron microscopic histochemical study of the composition of organic bone matrix at sites of beginning mineralization in mouse foetal radii, directing special attention to the presence and location of GAG. To demonstrate these substances, use was made of positive colloidal thorium dioxide and ruthenium red. The results demonstrate the presence of material containing acid groups in the young mineralization nodules. It is concluded that part of the demonstrated acid groups might be sulphate groups of glycosaminoglycans.