Histochemical localization of acid mucopolysaccharide in the respiratory muscles of a fresh-water air-breathing siluroid fish, Clarias batrachus (Linn.).

Respiratory muscles involved in gill ventilation (= irrigation) of an amphibious siluroid fish, Clarias batrachus (Linn.) were studied by phase contrast and light microscopy after the treatment with PAS. Alcian Blue at pH 2.5 and 1.0, dialyzed iron and Toludine Blue. The transverse muscle bands lightly stained with PAS, Alcian Blue at pH 2.5 and 1.0 and Dialyzed Iron suggesting that the mucopolysaccharide occured in relatively low concentrations. Phase contrast microscopy indicated that the transverse bands stained by the above mentioned reagents correspond to the I-bands. Methylation for 4 hours at 60 degrees C prevented I-band staining with Alcian Blue in the muscles studied. Saponification alone left I-band alcianophilia intact. These findings reveal that myofibrillar I-bands of respiratory muscles contain sulphated acid mucosubstances.