Restoration of reduced neuron numbers in double knockout (DKO) mice by disruption of complement C3 gene. (A) Spinal cord sections of 44- to 50-week-old mice stained with Klüver-Barrera (KB). Enlarged images indicated XI layer (motor neuronal region) in the spinal cord. (B) The numbers of motor neurons were counted in the spinal lamina XI of lumber spinal cord segments L3 and presented as the number of motor neurons. The thickness of sections was 5 μm (scale bar, 100 μm). The thickness of spinal lamina II + III was measured in lumber spinal cord segments L3 in wild-type (WT) and DKO mice and presented as the thickness of spinal lamina II + III. The numbers of spinal lamina II neurons and marginal cells in spinal lamina I were counted and presented as the number of neurons. The numbers of mice examined were as follows: 44- to 50-week-old WT (n = 4), DKO (n = 4), triple knockout (TKO) (n = 5), and C3KO (n = 3); data are presented as mean ± standard deviation (SD) and were analyzed by one-way analysis of variance (ANOVA) with Tukey-Kramer post hoc test (*P <0.05; **P <0.01; ***P <0.001).