Fig. 1: Med13l knockout mice exhibit microcephaly.

A Schematic diagram of the Med13l knockout strategy. Guide RNAs (gRNAs) were designed to target exon 2 to delete a 238 bp fragment, generating an early stop codon (magenta arrow and star). B Representative photographs of wild-type (WT), heterozygous (Het), and Med13l-knockout (KO) mouse littermates at birth (P0). Arrows indicate the presence or absence of milk in the stomach. Scale bar, 10 mm. C Survival rate of mice at P1. N = 33 (WT), 42 (Het), and 28 (KO). D Body weight of mice at P0. N = 11 (WT), 16 (Het), and 8 (KO). E Dorsal view images of brains from mice of different genotypes at P0. LC longitudinal cortex length, WC1, transverse cortex width; WC2, transverse cerebellum width. Scale bar, 2 mm. F Brain weight of P0 mice of different genotypes. N = 11 (WT), 18 (Het), and 12 (KO). G Comparison of the LC, WC1, and WC2 of P0 mice of different genotypes. N = 15 (WT), 19 (Het), and 10 (KO). H Representative images of P0 WT and KO brain sections stained for TBR1 (magenta) and CTIP2 (green), and with DAPI (blue). White dashed trapezoidal and rectangular boxes indicate the dorsolateral M1 region and dorsomedial ACC region, respectively, which are shown at higher magnification in (I). Scale bar, 500 μm. I High magnification images of the dorsolateral M1 region and dorsomedial ACC region of P0 mice stained for TBR1 and CTIP2, and with DAPI. Scale bar, 250 μm. J Quantitative analysis of the thickness of cortical layers of the dorsolateral M1 and dorsomedial ACC regions of the cortex. K Representative images of the VZ/SVZ region of P0 mouse brains stained for TBR2 (magenta) and DAPI (blue). Scale bar, 250 μm. L Quantitative analysis of the thickness of TBR2⁺ cell layer in the cortical VZ/SVZ at P0. Quantitative data are presented as Mean ± SEM and analyzed using one-way ANOVA followed by Bonferroni test in (D, F, G), and two-tailed Student’s t-test in (J, L). *p < 0.05; **p < 0.01; ***p < 0.001; ns not significant. Error bars represent SEM.