Figure 4 : SVZ progenitors were indispensable for cortical folding.

From: An essential role of SVZ progenitors in cortical folding in gyrencephalic mammals

Figure 4

IUE was performed at E32-E33, and the brain was prepared at P16. (a) Dorsal macroscopic images. Upper panels show bright field images, and lower panels show bright field images merged with GFP images. Although the coronal sulcus was clearly formed on the control brain (arrowheads), it was obscure on the DN-Tbr2-electroporated brain (arrows). Scale bar = 5 mm. (b) Coronal sections of the brain stained with Hoechst 33342. Broken lines indicate the surface of the brain. Note that the depth of the coronal sulcus was markedly shallower on the DN-Tbr2-electroporated side of the cortex (3′, arrow) compared with that on the GFP-electroporated cortex (1′, arrowhead) and the non-electroporated side of the cortex (2′ and 4′, arrowheads). (c) Serial coronal sections of the brain stained with Hoechst 33342. A, anterior. P, posterior. Broken lines indicate the surface of the brain. (d) Quantification procedures of gyrification. (e) Quantification of the local GI ratio. The local GI ratio was significantly reduced by DN-Tbr2 (n = 3 animals; *p < 0.05; Welch’s t-test). Bars present mean ± SEM. (f) Quantification of the local GDI ratio. The local GDI ratio was significantly reduced by DN-Tbr2 (n = 3 animals; *p < 0.05; Student’s t-test). Bars present mean ± SEM. (g) The cortical thickness of the posterior sigmoid gyrus divided by that of the coronal sulcus. The thickness(g/s) values were not affected by DN-Tbr2. (n = 3 animals; p > 0.05; Student’s t-test; N.S. not significant). Bars present mean ± SD. (h) The thickness of layer 2–4 relative to the cortical thickness (%L2-4) was measured, and the ratio of %L2-4 in the posterior sigmoid gyrus to that in the coronal sulcus [%L2-4(g/s)] was calculated (n = 3 animals; *p < 0.05; Student’s t-test). Bars present mean ± SD. (i) The thickness of layer 2–4 relative to that of layer 5–6 (L2-4/L5-6) was measured, and the ratio of L2-4/L5-6 in the posterior sigmoid gyrus to that in the coronal sulcus [L2-4/L5-6 (g/s)] was calculated (n = 3 animals; *p < 0.05; Student’s t-test). Bars present mean ± SD.