Postnatal development of masticatory organs in rats. III. Effects of mastication on the postnatal development of the M. masseter superficialis.

When suckling of rats was continued on days 17--25 after birth, the development of the M. masseter superficialis was inhibited: increase in the diameter and SDH activity of its muscle fibers was retarded. Conversely, forced weaning of rats on 17 after birth stimulated the development of the muscle. These results suggest that mastication after weaning is involved in the further postnatal development of the M. masseter superficialis in rats.