Histochemical profile of muscle spindles of rat's sural muscles.

The histochemical profile of intrafusal fibres of muscle spindles and muscle spindle capsule were analysed in normal sural muscles of a rat. Weak activity of oxidative enzymes (NADH diaphorase, succinic dehydrogenase, lactate dehydrogenase) and creatine phosphokinase were found in bag1 and bag2 fibres, but the oxidative enzyme activity was moderate in chain fibres. High phosphorylase activity was demonstrated in bag fibres as well as in chain fibres. No differences could be detected in adenosine desaminase activity between these various intrafusal fibres. In the outer capsule of muscle spindles, high amount of type III collagen and elastin, but only small amount of type I collagen and fibronectin could be observed.