Histochemical demonstration of skeletal muscle fibre types and capillaries on the same transverse section

Summary. Serial transverse sections of m. vastus lateralis biopsies from six healthy men were reacted:

• 1 for myofibrillar adenosine triphosphatase (mATPase) to identify fibre types;
• 2 with α-amylase, periodic acid-Schiff (αPAS) to visualize capillaries. Sections were also processed with a new histochemical method for identification of fibre types and capillaries on the same skeletal muscle slice (mATPase/αPAS). Fibre type composition using either method was 41% type I, 37% type IIA and 22% type IIB. Types I, HA and IIB least diameter areas (mean±SE, μm²) were similar in sections processed for mATPase/αPAS or mATPase (3976±338, 5187±373 and 4389±514 vs. 4092±345, 5100±360 and 4289±474, respectively). The number of capillaries per mm² and per fibre did not differ in sections processed using the αPAS (315±29 and 1·48 ±0·12) or mATPase/αPAS (317±25 and 1·43±0·10) method. The number of capillaries was greater (P<0·05) around types I or IIA than type IIB fibres whether a section was processed for mATPase/αPAS (4·5±0·2 or 4·6±0·2 vs. 3·4±0·3) or when fibre profiles of serial sections reacted for mATPase or αPAS were ‘matched’ (4·5±0·2 or 4·4±0·2 vs. 3·4±0·3). The results indicate that histochemical and morphometric measures can be made on the same transverse section using the new method with substantial savings of time, cost and energy.