Fig. 2

Developmental stage and axon fragment size regulate the rate of WD. (A) Quantification of the number of axon fragments versus time after axotomy in two 54 hpf (purple lines) and two 30 hpf (red lines) embryos. Fragmentation occurred at the peaks in the graph, which was much earlier in 54 hpf embryos. Thirty hpf embryos had a longer lag phase and fragmented into fewer axon fragments because axons were still growing and severed branches were therefore smaller. (B) The lag phase at 30 hpf was significantly longer than the lag phase in both 54 hpf (P=0.0001) and 78 hpf (P<0.0001) embryos, but the difference in lag phases between 54 hpf and 78 hpf was not significant (P=0.1578). The clearance phase occurred at the same rate at all ages examined (Pe0.2844). Error bars indicate s.e.m. (C) Quantification of lag phase length versus total axon fragment length. Scatter plot trendline indicates no correlation (r=0.09663) (n=20). (D) Quantification of clearance phase length versus total axon fragment length. Trendline indicates a modest correlation (r=0.3813) (n=20). (E) Confocal image stack projections of a 54 hpf embryo expressing GFP in all sensory neurons and RFP in a subset of sensory neurons. The entire trigeminal ganglion was ablated on the right side (left image, 2.5 hours after axotomy), and RFP-labeled debris remained 12.5 hours after axotomy (right image, higher magnification of boxed area in left image).