Fiber Lengths and End-plate Locations in Fruit Bat Web Muscles ∗

Summary

Single motor nerve fibers to bat web muscles were stimulated in vivo, and both ends of single muscle fibers were located by the presence of monophasic action potentials. The mean length of 12 such muscle fibers was 10.1 mm. Electrical responses of minimum latency were recorded in 6 of these fibers, demonstrating end-plate loci within the middle two quarters of muscle fibers, generally close to the middle. In addition, 71 muscle fibers were isolated after acid treatment. Mean length of 57 intact fibers was 14.1 mm and of 14 fibers with missing tips was 10.1 mm. The 14 fibers with missing tips and one intact fiber were stained for “lead-reactive substance” to locate their end-plates, which were within the middle two quarters of the fibers.