Figure 1. Slow-type muscle fiber switch during hibernation.
A, Immunofluorescent staining of squirrel quadriceps muscle reveals the relative abundance of Type I, IIA, and IIB fiber types. Scale bar 100 μm. B, Comparison of muscle fiber type percentages between muscle from non-hibernating and hibernating squirrels. During hibernation there is a significant increase in slow-twitch, Type I muscle fibers and a decrease in fast-twitch, Type IIB fibers. (*P<0.05; **P<0.01)