Further Studies on Histochemical and Ultrastructural Properties of the Pectoral Muscles of Bats

The pectoral muscles (anterior division) of two bat species with different modes of flight were investigated histochemically and ultrastructurally. According to the histochemical study, the pectoral muscles of Miniopterus schreibersi fuliginosus which can fly a long distance with speedy and enduring flights were constituted with two muscle fiber types (mitochondria-more rich and mitochondria-moderate fibers), while those of Rhinolophus ferrumequinum kppon which can fly slowly and delicately were composed of three muscle fiber types (mitochondria-more rich, mitochondria-less rich and mitochondria-moderate fibers). As to the distinctive ultrastructural features of the three muscle fiber types, sarcoplasmic reticulum and the folds of neuromuscular junction were more developed in the mitochondria-more rich and mitochondria-moderate fibers of both species than in the mitochondrialess rich fiber. It is concluded that there is a correlation among fiber composition and ultrastructural features, and physiological properties of the pectoral muscles needed for different types of flight