Histochemical demonstration of three types of muscle fibers of the intercostal muscles. A study on oxidative enzymes

Since the classic work of Ranvier, it is well known that the mammalian striated muscle is composed of two types of muscle fibers, i. e., the red and white muscle fibers. In the previous paper1 it has been reported that the limb muscle fibers of mammals can be divided into three types from their activities of the histochemically demonstrable oxidative enzymes. Namely, the small red muscle fibers had a higher activity of oxidative enzymes, the large white muscle fibers a lower activity and the third type of muscle fibers being called "medium fiber" or "intermediate fiber" showed an intermediate activity between those of the red and white muscle fibers.