Growth of Skeletal Bones and Their Sexual Differences in Mice

Abstract

An experiment was conducted in 76 mice (3 to 9 weeks of age) to investigate the characteristics in growth of major skeletal bones and their sexual differences. The length of ulna, radius, femur and tibia attained their maximum growth rate at earlier age, and showed no sexual difference in their growth patterns. Scapula length and width, humerus length and os coxae width reached the maximum growth rate at a later age than the forearm and shank, and showed no sexual difference in their growth, although those bones presented larger adult sizes for male than female. The length of vertebrae showed significant sexual differences in their growth patterns and adult sizes, except for lumber vertebrae. A significant sex difference in body weight caused the sexual differences in relative growth of bones to body weight. According to their relative growth to the length of humerus, the skeletal bones could be well grouped into three categories. A significant sexual difference was seen in the relative growth of scapula length. In general, it seemed that the bones growing in a vertical direction grew earlier than the bones growing in a horizontal direction, especially those of the forearm and shank. The results obtained in mice were in good agreement with the findings in pigs.