NMJs in sternomastoid muscles of adult mice lacking FGF-5 stained for nerve (a, b) and AChRs (a′, b′) as in Figure 1. a, The mutant NMJ is indistinguishable from controls (compare with Fig.1a). b, Terminal sprouting from an intact end plate in an FGF-5^−/− muscle 7 d after partial denervation. The sprout (arrow) resembles those seen in controls (compare with Fig. 8a). Scale bar, 20 μm.