Fig. 5.

Lack of α7 integrin subunit causes a delay of target reinnervation in the axotomized facial nerve.a–c, Experimental model. a, Fluorogold was applied into both whiskerpads 2 d before killing, retrogradely transported by normally connected (control side, Co) and reinnervating motoneurons (axotomized side, Ax), and detected in the brainstem (b) at different time points after facial nerve crush. The onset of whiskerpad reinnervation is observed between day 7 and day 9. c, Time course of whiskerpad reinnervation, with total number of FG-positive motoneurons (FG + MN) on the axotomized side, expressed as percentage of the number on the contralateral side; six brainstem sections were counted per animal. Scale bar, 100 μm. d, Effect of α7 deficiency on whiskerpad reinnervation 9 and 21 d after facial nerve crush. Unlike the α7+/+ mice (n = 4), no FG-positive motoneurons were found in the axotomized, facial motor nuclei of the α7−/− animals (n = 5) at day 9 (p < 0.05%, Wilcoxon test). Both groups of animals (n = 4) showed a similar reinnervation index at day 21. The horizontal bar shows the mean percentage per group.