Role of endogenous zinc in bones of newborn rats.

Concentration of abundant elements e.g. calcium as well as of elements present in trace amount e.g. zinc in mandibles of 7, 14 an 28 day old newborn rats were determined by X-ray fluorescence analysis. The measurements were carried out by using a measurement system containing X-ray tube ECLIPSE-III and X-ray and gamma ray detector XR-100T-CdTe (Amptek Inc.). Concentration of calcium and zinc depended on the region of interest on the rat's mandible due to mineralization degree conditioned by its function. Increasing age produced a remarkable increase in Ca content in contrast to Zn content in the bone tissue obtained from 7, 14 and 28 day old newborn rats. The calculated Zn/Ca concentration ratio was the biggest for 7 day old newborns and successively decreased with age indicating the important role of zinc at the beginning of bone ontogenesis.