Figure 2

p75^−/−mice show reduced branching and mid-region tongue innervation on embryonic days 14.5 and 16.5. DiI-labeled chorda tympani axons in wild-type (A,D,F) and p75^−/−mice (B,C,E,G) on embryonic day (E) 14.5 (A,B,C) and E16.5 (D,E,F,G). In p75^−/−mice, chorda tympani branching was reduced, and innervation often did not reach the tongue surface as neural buds. Nerve branches were particularly absent from the tongue mid-region (B,C,E). By E16.5, nerve fibers reached the tongue tip in p75^−/−mice, but branching and neural bud number was reduced (F,G). Scale bar = 250 μm.