In this study, taking the extensor muscle out of the pectoral fin of trout, lipid and mitochondria contents of muscle fibres were examined. Succinic dehydrogenase and Sudan black B stain methods were applied on the sections removed by freezing microtomy. Haematoxylen and eosin staining were also applied on the sections obtained from paraffin blocks. It was observed histologically that nuclei of muscle fibre were located just under the sarcolemma. Three types of fibres red, intermediate and white were identified by the applied histochemical methods. It was observed that this muscle was rich in red and intermediate fibres. As a result, it was found that the diameter of red, intermediate and white fibres were 66.6 m m, 93.3 m m, and 133.3 m m, respectively.

In this study, taking the extensor muscle out of the pectoral fin of trout, lipid and mitochondria contents of muscle fibres were examined. Succinic dehydrogenase and Sudan black B stain methods were applied on the sections removed by freezing microtomy. Haematoxylen and eosin staining were also applied on the sections obtained from paraffin blocks. It was observed histologically that nuclei of muscle fibre were located just under the sarcolemma. Three types of fibres red, intermediate and white were identified by the applied histochemical methods. It was observed that this muscle was rich in red and intermediate fibres. As a result, it was found that the diameter of red, intermediate and white fibres were 66.6 m m, 93.3 m m, and 133.3 m m, respectively.