An alternative histochemical method to simultaneously demonstrate muscle nuclei and muscle fibre type.

We present a modified histochemical method to examine, simultaneously, nuclei and fibre type in human skeletal muscle. The new procedure (Haem-ATPase) is based on two previously used histochemical protocols. Biopsies were obtained from the rectus abdominis muscle of patients undergoing elective abdominal surgery. Fibre type composition, cross-sectional area (CSA) and nuclei to fibre ratio (N:F) were determined from frozen sections of each biopsy. To test the validity of the new method, serial sections of each biopsy were stained separately using the standard and modified methods. No differences were found in fibre type distribution, mean-weighted CSA and N:F when comparing the modified method with the standard methods. The Haem-ATPase method was found to shrink fibre size by at least 3% ( P>0.05) compared with the established myosin acid labile method. We propose that this modified technique is suitable for initial examination of both the nuclei and fibre type in the same frozen sections of human skeletal muscle.