[Comparative studies on bone growth in experimental animals. 1. Bone growth and ossification in mice (author's...

Comparative studies are needed on the bilogical stage of the bone growth in experimental animals and human to extrapolate the data from animals to for estimating the risk of bone seeking redionuclides in man. The growth of bone length and the appearance and fusion of the secondary ossification centers of seven long bones were compared between both species. The stage of ossification was determined radiographically. The results showed that the ossifying process of the secondary ossification centers could be divided into the following three categories in mice; (1) acute ossification type, (2) remaining metastable stage type which is specific in mice and generally at the proximal end of bone, and (3) delayed ossification type. Compared with the average life span, differences in ossification between both species were that the appearance of secondary ossification centers was observed within concentrated period in mice and not in man, and that the fusion of these was observed with long duration in mice and not in man. From 17 weeks of age, the metastable status of the bone appeared in mice without complete fusion even at 27 weeks of age, for the experiment with bone seeking radionuclides, mice of age 17 weeks or more should be used consequently.