OBJECTIVITY OF 2 METHODS OF DIFFERENTIATING FIBER TYPES AND REPEATABILITY OF MEASUREMENTS BY APPLICATION OF THE TEMA IMAGE-ANALYSIS SYSTEM

The objectivity of two of the most widely used methods for differentia tion of fibre types, i.e. 1) the myosin ATP-ase method (Brooke and Kai ser, 1970a,b) and 2) the combined method, by which the myosin ATP-ase reaction is used to differentiate between fast and slow twitch fibres and NADH-tetrazolium reductase activity is used to identify the subgro ups of fast twitch fibres (Ashmore and Doerr, 1970, Peter et al., 1972 ), was assessed in muscle samples from horses, calves and pigs. We als o assessed the objectivity of the alpha-amylase-PAS preparation for th e visualisation of capillaries (Andersen, 1975) in these species. For the purpose of reducing the time costs of histochemical analysis of mu scle samples, we have developed an interactive image analysis system w hich is described. All analyses are performed on this system. In accor dance with several other investigations, differences between the two m ethods of differentiating fibre types were found only for the relative distribution of the fast-twitch fibre subgroups (p < 0.02 and p < 0.0 5 for the relative number of type IIA and IIB, respectively) whereas w hen calculated in relative area, only the proportion of type IIA fibre s differed significantly (p < 0.05). Significant interaction effects b etween method and person and method and species were found for the sam e traits. When methods were analysed separately, the combined method d isplayed a significant variance component of person for the distributi on of type IIA fibres both in relative number and in relative area (p < 0.01 and p < 0.001, respectively). The objectivity of the ATP-ase me thod was further substantiated by the fact that a higher fraction of t he total variance for the relative area distribution of type IIA fibre s was explained by the statistical model (72.1% versus 34.2% for the c ombined method). Although the repeatability of measurements between pe rsons was generally high (> 87%), the impact of differences in prerequ isites (varied degrees of overlap between the fibre types) for perform ing the differentiation by the combined method raises a question of th e reliability of this method. Apparently, no general rules for compari son of results of distribution of the two supgroups of fast twitch fib res by the two methods are applicable. The alpha-amylase-PAS method wa s found to be a fairly objective method to identify capillaries in mus cles from horses, calves and pigs. However, as capillarity described i n combination with other traits to give an indication of diffusion cha racteristics is significantly influenced by person, it is recommended that the same person perform all the analysis of a project. In additio n to the methodological results in this study, we have shown that by a pplication of the TEMA image analysis system, which is more rapid comp ared with the time-consuming traditional method for evaluation of hist ochemical preparations, analysis of samples from large-scale experimen ts are now possible.