Quarterly Journal of Microscopical Science, Vol s3-102, 131-141, Copyright © 1961 by Company of Biologists

Histochemical Observations on the Succinic Dehydrogenase and Cytochrome Oxidase Activity in Pigeon Breast-muscle

¹ Laboratories of Animal Physiology and Histochemistry, Department of Zoology, M.S. University of Baroda, Baroda, India

Histochemical and cytochemical observations were made on the exact localization and distribution pattern of succinic dehydrogenase system and cytochrome oxidase in the pigeon breast-muscle by employing slightly modified methods. Succinic dehydrogenase activity, which was not detected earlier either histochemically or biochemically in the broad white fibres, was demonstrated by using a modified incubation medium under strictly anaerobic conditions, with neotetrazolium as the hydrogen acceptor. The size, localization, and distribution pattern of the histochemically demonstrable diformazan and indophenol blue granules showed a more or less close resemblance to the mitochondrial staining in the individual red as well as white fibres. The occurrence of high oxidative metabolism in the narrow red fibres was revealed by the presence of a large number of succinoxidase-positive granules in these fibres. On the other hand, the presence of fewer, smaller granules indicated very low oxidative metabolism in the broad white fibres.

The presence of the fewer, smaller succinoxidase-positive granules in the broad white fibres nevertheless shows that these fibres too possess mitochondria where at least a certain amount of oxidative activity does take place, and that they are to be considered as analogous to the white fibres of the other vertebrate skeletal muscles. It is also suggested that these granules are to be considered as mitochondria in the general sense and that the distinction between sarcosomes and mitochondria as proposed by previous authors needs reconsideration.