Classification of pig myofibres and assessment of post-mortem glycogen depletion according to fibre type by computerized image analysis

A computer-aided method for muscle fibre type determination and qualitative analysis of glycogen at a cellular level is described. The operational system consists of a microscope, a CCD videocamera, an image analysis card, a colour monitor and a standard workstation computer (32 Mb central memory, 22 mips) running under the UNIX operating system. The programme was developed with 512 × 512 pixel images. Four main steps can be distinguished: digitization, network extraction, network matching and measurement of staining intensities. The data generated for each analysed fibre included, diameter, cross-sectional area, ATPase staining intensity and type. Ten minutes of batch processing and 36-41 min of interactive work were needed to analyse 200-300 fibres. Results have shown that this image analysis system can distinguish four types of myofibres denoted I, IIA, IIB and IIC, on the basis of myosin ATPase sensitivity at three preincubation pH values (4·10, 4·35 and 10·4). Preliminary results have also shown that the image analysis system can be used to measure post-mortem glycogen depletion according to fibre type.