A general, computer-based method for study of the spatial distribution of muscle fiber types in skeletal muscle.

The present method provides detailed quantitative information on the spatial distribution of the muscle fiber types in skeletal muscle. This is accomplished by comparing the measured spatial distribution of the fiber types with a computer-simulated random pattern. The method is based on a registration of the absolute frequency for six principal categories of fiber contacts (I-I, I-IIA, I-IIB, IIA-IIA, IIA-IIB, IIB-IIB). A computer program was designed to simulate a random pattern of fibers. The simulations were performed with high accuracy with regard to fiber type proportion and the number of neighbouring fibers. The computer then calculated the frequency for each of the different categories of fiber contacts in the simulated random pattern. The measured distribution of fiber contacts could thus be compared to the simulated random pattern. In three bovine muscles studied, the spatial distribution of the muscle fiber types showed a similar pattern. The muscle fibers had a distinct tendency to be surrounded by fibers of a different type. In all three muscles the difference between the measured and the simulated random pattern was statistically significant (p less than 10(-3).