The relationship between motor endplate size and muscle fiber diameter in different muscle groups of the rat.

To investigate the relationship between motor endplate size and muscle fiber diameter, analyses of 125I-alpha-bungarotoxin autoradiographs and acetylcholinesterase staining were performed in different muscle groups of the rat. These revealed 1) there is a linear correlation between endplate size and fiber diameter in each muscle group, and 2) each muscle group has a characteristic ratio of endplate size to fiber diameter; the ratios were markedly higher in extraocular muscles than in limb muscles.