Role of vitamin D in the osteogenesis of bone in tissue culture.

Abstract

The physiological role of vitamin D in osteogenesis and calcification is not yet understood. It has been suggested that in vivo the vitamin promotes the calcification of bone by an indirect action mediate through the intestine or liver. Recently WASSEI~MAN and TAYLOR (1966) have shown that in the presence of vitamin D calcium protein complex is produced in the intestine. It seems also possible that this calcium protein complex is produced in the liver, which may prove to be the normal calcifying agent. I#o one so far has succeeded in improving calcification of either osteoid matrix or dentine formed in organ culture by adding vitamin D into the medium. Experiments have been carried out in two stages. In the first series of experiments ten dogs were operated, and the blood samples were collected from the isolated pre-hepatic and post-hepatic veins, before and after the administration of vitamin. The level of water soluble calcium, total calcium and protein bound calcium were estimated. In the second series of experiments, tibiae of 14 days old chick embryos were cultured for eight days in control me~lium (B.G.J.) and in the medium containing vitamin D treated serum. The increase in length, wet and dry weight was measured. After measuring the weight, bones were subjected for biochemical analysis like hexosamine and hydroxyproline estimation. The histological, histoehemical and autoradiographic studies were also carried out. Evidences will be presented that vitamin D produces resorption of bone directly (in vitro) and increases the osteogenesis indirectly.