Figure 4.

Analysis of facial nerve sprouting by transmission electron microscopy. (a–d) Three days after injury, unlesioned (a,b) and lesioned (c,d) facial nerves of wt (a,c) and Atf3 mutant (b,d) animals were analysed by EM for the presence of nerve sprouts. In unlesioned nerves, only few axons contained sprout-like structures (a,b). By contrast, lesioned axons contained axonal sprouts (arrows in c,d) with a neck and bulb-like terminal structure (c,d). (e) Quantification of the percentage of axons with sprouts in relation to the total number of axons. In lesioned nerves of wt mice, the number of axons with sprouts was significantly elevated compared with nerves derived from ATF3-deficient animals. Each circle or square represents one mouse. Data are presented as mean ± s.d. *p ≤ 0.05. Scale bar (a–l) = 5 µm.