Abstract
Intrafusal muscle fiber can be classified into two histochemical types based on ATPase reaction; type 1 with low ATPase activity and type 2 with high activity.
The left crural muscles of rats were denervated by crushing the sciatic nerve and contralateral muscles were used as a control. The intrafusal muscles of the musculi ext. dig. longus were observed and their transverse areas were measured. The following results were obtained:
1. The standard rat muscle spindle has three type 1 fibers and one type 2 fiber.
2. Type 1 fibers showed more severe atrophy than type 2 fibers after denervation.
3. The area of the type 2 fiber became larger after denervation.
The above observations were consistent with our observations of extrafusal muscle.
