Enzyme histochemistry of skeletal muscle. I1I. Neurogenic muscular atrophies

As discussed in the preceding paper (Dubowitz, 1965), it is possible with histochemical techniques to recognize two fibre types in human skeletal muscle, and to follow the sequence of differentiation of muscle into these fibre types in the course of foetal development. The type I fibres are rich in certain oxidative enzymes such as NADH (nico-tinamide-adenine dinucleotide) diaphorase and poor in phosphorylase, while type II fibres are rich in phosphorylase and also other enzymes such as myosin adenosine triphosphatase (ATPase) but poor in the Krebs cycle oxidative enzymes (Fig. 1). In an application of these methods to pathological muscle (Dubowitz and Pearse, 1961), we observed in two cases of neurogenic atrophy that the isolate