Physical and biochemical changes of the mandible and long bone in protein-energy malnourished newborn rats.

The activities of alkaline and acid phosphatases, the linear dimensions and volumes of mandibles and long bones, and the level of calcitonin in serum of rat pups suckled on dams fed 25 or 6% protein diets were determined. In both mandibles and long bones, alkaline phosphatase activity corresponded to the calcification pattern, and acid phosphatase activity paralleled organic matrix formation. The calcitonin level in blood serum of the malnourished pups differed from that of controls only on day 5. The linear dimensions and volume were consistently more affected in long bones than in mandibles. These results may be explained in terms of the critical growth periods of these bones. In the mandible, the critical growth period appears to occur prenatally, whereas in the long bone it occurs postnatally, when the nutritional stress of this experiment was applied. Long bones were thus generally more affected than mandibles.