A simple test for the random arrangement of muscle fibres

The random arrangement of a given muscle fibre class has been assessed by estimating 'mean cluster size' in transverse sections of skeletal muscle. The method was found to be useful when the proportion of the fibre class of interest was low. The statistical distribution of this measure was investigated by computer simulation using a hexagonal lattice model of muscle fibre arrangement. An approximate significance test was developed by considering the extreme points of the distribution. Minor changes to the hexagonal lattice model were incorporated to give a more realistic representation of fibre arrangement and these were found to give very similar results to the simpler model.