Total Number of Fibers in Muscles of Several Strains of Mice

The total fiber numbers in the biceps brachii, anterior tibialis, extensor digitorum longus and the soleus muscles were examined in four strains of mice, C57, CIF, IF and dba. There were in some cases, significant differences in mean body weight and both absolute and relative muscle weights among the strains. Significant strain differences in mean total fiber numbers were noted for all muscles except the extensor digitorum longus. No consistent significant correlation was found between muscle weight and total fiber numbers.