Figure 3: Morphological analysis of the brains of Rev3l embryonic and newborn mice.

(a) Example of a sagittal section of the embryonic mouse head at E16.5 stage used for subarachnoid volume rendering, processed with Nissl staining. The subarachnoid space is shown in green. Scale bar, 1 mm. Right: subarachnoid volume rendering measures of both genotypes. In all Rev3l heterozygous embryos the subarachnoid space is significantly increased as compared with wt embryos (Unpaired t-test P value=0.0047, N=5). Scale bar, 500 μm (b) Example of one of the hindbrain sagittal sections at P0 used for hindbrain volume rendering. We measured the volume of five wt and five heterozygous mice. The hindbrain boundaries are indicated by dashed lines. Scale bar, 500 μm. Right: Rev3l heterozygous mice show a significant decrease of hindbrain volume (Unpaired t-test P value=0.015, N=5). (c) Lateral hindbrain sections at the P0 stage of a view of the facial motor nucleus, inside the square. Scale bar, 300 μm. (d) Higher magnification of the facial motor nucleus showing paucity of Rev3l heterozygous motoneurons. Scale bar, 100 μm. Right: quantification of motoneurons in the facial motor nucleus, in each side of the hindbrain, in five wt and five heterozygous P0 mice (mean±s.d.). The difference is statistically highly significant (Unpaired t-test P value<0.0001, N=10). We do not show both genotypes because there are no visible differences between them. 5N, trigeminal nucleus; 7N, facial nucleus; Cb, cerebellum; HB, hindbrain; Is, isthmus; r1–r11, rhombomeres r1 to r11; Sb, subarachnoid space; Sk, skull; SpC, spinal cord. A P value smaller than 0.05 was considered to be statistically significant (*). P values smaller than 0.01 (**) or 0.001 (***) were considered highly significant.