Histochemical Differentiation of Red and White Muscle Fibers

The longissimus dorsi was much lower in red fiber content than the trapezius. A reciprocal relationship was found between the enzymes DPNH-TR and amylophosphorylase in individual fibers. The classical red fibers reacted positive for DPNH-TR and negative for amylophosphorylase; the converse held for white fibers. Fibers intermediate between the characteristic red and white were observed.