Histochemistry of some trout respiratory muscles

Summary A histochemical study has been made of the main cranial muscles which produce ventilation movements of the rainbow trout. It is shown that a greater proportion of red(aerobic) fibres is present in those muscles known to be active during shallow ventilation than those which become active at greater ventilation volumes. An ordered recruitment of red, pink and white fibres within these muscles is also likely.This work was carried out when I.A. Johnston was holding an NERC Post-Doctoral Research Fellowship (1973–75).