ELECTRON MICROSCOPY: MUSCLE: Fibroblast, endomysium, skeletal muscle. (EM-labeled); RCH/AMC962, rat soleus muscle, endomysial fibroblast, edge of skeletal muscle fiber. 1-Golgi apparatus of fibroblast, 2-mitochondrion of fibroblast, 3-myofibril, 4-mitochondrion of skeletal muscle fiber, 5-unmyelinated axon