An electron microscopical study on the presence of proteoglycans in the calcified bone matrix by use of cuprolinic blue.

With Cuprolinic Blue (CBl) as contrasting agent, PGs could be demonstrated in mouse fetal bone matrix. Large CBl-positive rod-like structures proved to be present in and outside the calcification nodules in regions of beginning mineralization. In further developed bone also smaller rods were present in the mineralized matrix. The CBl-positive rods were sensitive to chondroitinase ABC and hyaluronidase. Under the circumstances we chose, this indicates that these structures are PGs containing chondroitin and/or dermatan sulphate. The fine filamentous and granular material in the nodules was still present after digestion with these enzymes, but disappeared after treatment with pronase. This is an indication that this material mainly contains proteins.