A histochemical study of the red and white muscle fibers Part I. Activity of the succinoxydase system in muscle fibers

From the histochemical studies of succinic dehydrogenase on the striated muscle of the fish, frog, bird and mammal, the following results were obtained. (1) The red muscle fiber shows a higher succinic dehydrogenase activity, while the white muscle fiber a lower activity. The third type of muscle fiber "medium fiber", which is intermediate in the succinic dehydrogenase activity between the red and white muscle fiber, is observed practically in all of the striated muscle of mammals. (2) There is a good parallelism between succinic dehydrogenase activity and stainability to Sudan black B among the three types of muscle fibers. (3) From the nature of the constituent fibers, muscles can be divided into three groups, i. e., gastrocnemius type, soleus type and diaphragma type. (4) Those belonging to the gastrocnemius type are composed of three types of fibers, i. e., those of large size, low in activity of succinic dehydrogenase reaction and low in sudanophilicity; those of small size, high in enzymatic activity and in sudanophilicity; and those of medium size, moderate in enzymaticactivity and in sudanophilicity. (5) Those belonging to the soleus type, are composed of fibers almost equal in size which can be divided into two by the enzymatic activity and sudanophilicity, excepting the few with low enzymatic activity. (6) Those belonging to diaphragma type, are composed of three kinds of fibers showing different enzymatic activity as in the case of gastrocnemius type, but there is no correlation between the size and the enzymatic activity and sudanophilicity differing from the latter. (7) The difference in succinic dehydrogenase reaction as demonstrated among three types of fibers is due to the difference in number or in activity of mitochondria. (8) The pigeon breast muscle is composed mostly of red muscle fibers, and a few white muscle fibers, while the sparrow breast muscle is composed only of red muscle fibers. (9) The bloody colored muscle of the fish corresponds to the red muscle of the mammals. The white muscle of the fish is composed of three types of fibers. (10) The frog muscle is cmposed of three types of fibers.