Histochemistry of fibres of masseter and temporalis muscles of edentulous monkeys Macaca mulatta.

Muscle fibres of the masseter and temporalis muscles of female rhesus monkeys which had been edentulous for 4.5 yr were analysed histochemically. Fibres were classified on the basis of activities of succinic acid dehydrogenase and myofibrillar adenosine triphosphatase. Capillaries were visualized by phosphatase activity. Succinate oxidase activity was determined by differential respirometry of aliquots of whole muscle homogenates. These data were compared to data obtained from the muscles of control adult female animals. Relative to control values, the muscles of edentulous animals had lower oxidative capacity, more fast fatigable (FF) and fewer fast fatigue resistant (FR) and slow fatigue resistant (S) fibres, smaller S fibres and slightly reduced capillarity. These data indicate relative disuse of elevator muscle following removal of teeth.