Osteoid: an ultrastructural study.

Iliac crest bone biopsy specimens from 34 patients were examined with the electron microscope. Although the biopsy examinations were undertaken because of suspected metabolic or hematopoietic disease, neither clinically nor by light microscope was any evidence of disease identified. The layer of bone matrix between the osteoblast and the mineralized bone, usually referred to as "osteoid," is found not to be a homogeneous mass but to show a constant sequence of maturation and organization of collagen fibrils and mucopolysaccharides. This pattern was found to be modified in a situation of rapid bone formation such as normal fetal bone or in disease states such as Paget's disease of bone. These observations are of paramount importance in the evaluation of metabolic diseases of bone and in the identification of bone formation by mesenchymal neoplasms.