Abstract
In Japan, about 3 to 4 months after birth is widely accepted as the appropriate stage of lip plasty but some insist on operating a few days after birth or after 6 months. Natsume of our department investigated the orbicularis oris muscle which plays and important role in lip plasty morphometrically during development of rabbits. He suggested human lip plasty should not be performed before 3 months after birth.
Subsequtently the author intended to examine the stage of lip plasty biochemically by analyzing the myosin changes during development, and then to clarify the growth process of orbicularis oris muscle in rabbits.
Total activity of myosin Ca2+-ATPase in pure orbicularis oris muscle from the median area of lower lip was taken up as an index of the muscle development, and myosin Ca2+-ATPase activity per mg muscle protein was used as an index of its differentiation.
The results were as follows:
1. The variance of total activity of myosin Ca2+-ATPase during development was approximately the same as that of the weight of orbicularis oris muscle.
2. The variance of myosin Ca2+-ATPase activity per mg muscle protein which was considered the important factor of muscle differentiation, presented the figure of 3 peaks. This suggested that there were differences in the stage and the rate of accumulation between myosin and other muscle proteins.
3. Myosin of gastrocnemius muscle was chiefly accumulated in the growing stage. So it was supposed that orbicularis oris muscle was differentiated in the early stage.
4. Supposing that lip plasty should be done after differentiation of orbicularis oris muscle, it seemed that the appropriate stage of the lip plasty was more than 40 days after birth in rabbits and more than one year after birth in human.
