Figure 4.

Figure 4. Microglia are necessary for brain tissue repair.

(A) Example of simulation result showing microglia accumulation and wound closure. Left: simulated tissue after injury with patches of microglia agents in the neuropil. Right: the same simulation at 24 hpi. (B) Relation between the repair index estimated on the simulated data and the number of microglia agents in the simulation. (C) Images of an injured tectum in WT and irf8–/– Tg(Xla.Tubb:DsRed) larvae, right after the injury (0 hpi) and at 24 hpi. The orange dashed lines show where the injury was made. The white dashed lines show the analysis regions for calculating the repair index. Scale bar: 20 µm. (D) Quantification of the repair index (=1 - V@24 hpi/V@4 hpi) in WT (n = 21) and ifr8 mutant larvae (n = 17). t test P-value <0.001. (E) Correlation analysis of the repair index versus initial injury volume shows that the repair index is independent of the initial size of the injury. (F) Trajectories of neuronal cell bodies in an injured irf8 mutants (Scale bar: 50 µm). (G) Comparison of anisotropy of trajectories in WT (orange, from Fig 1I) and in ifr8 mutants (black). (H) Quantification of the depletion of microglia using KI20227 t test P-value <0.0001 (Controls n = 4, treated n = 10). (I) Measurement of the repair index in control (n = 12) and KI20227 treated (n = 26) animals. t test P-value <0.0001. Box plots show the median, box edges represent the 25th and 75th percentiles, and whiskers show the full data range. Scale bars represent 50 µm on all images.