Characterization of csf1 r ^DM mutant. (A) Representative images of myelin in wt and csf1r^DM Tg (mbp:EGFP-CAAX) spinal cords. (B−D) Quantifications of myelinated area (B), number of oligodendrocytes (C), and sheath lengths (60 individual myelin sheaths from n = 3 fish; D) in the dorsal spinal cord of 4 dpf wt and csf1r^DM larvae (wt: n = 8, csf1r^DM: n = 9 larvae in B and C). Two-sided Student’s t test: P = 0.5359 (B), P = 0.0905 (C), Mann–Whitney U-test: P = 0.8445 (D). (E−G) Quantifications of myelinated area (E), number of oligodendrocytes (F), and sheath lengths (60 individual myelin sheaths from n = 3 fish; G) in the dorsal spinal cord of 10/11 dpf wt and csf1r^DM larvae (wt: n = 10, csf1r^DM: n = 11 larvae in E and F). Two-sided Student’s t test: P = 0.0012 (E), P = 0.0001 (F), Mann–Whitney U-test: P = 0.3419 (G). (H) Number of mpeg1:EGFP-positive microglia per spinal cord in 4 vs. 7 dpf wt and csf1r^DM larvae (4 dpf: n = 8, 7 dpf: n = 7 larvae). Two-way ANOVA with post-hoc Sidak’s test: 4 dpf, wt vs. csf1r^DM: P = 0.0266, 7 dpf, wt vs. csf1r^DM: P < 0.0001. (I) Quantification of the number of myelin abnormalities in 18 dpf ventral spinal cord of wt and csf1r^DM larvae, normalized by the myelinated area (n = 13 larvae). Two-sided Student’s t test: P = 0.0002. Data represent means ± SD. ns, not significant, *, P < 0.05, **, P < 0.01, ***, P < 0.001, ****, P < 0.0001. Scale bar: 10 µm (A).