Fig. 4: Conditional deletion of Trio in GABAergic INs delays their tangential migration.

A–E GABAergic IN migration at e13.5 is delayed in Trio^cKO brains. Examples of immunostaining on coronal brain sections from e13.5 mouse embryos of (A) Trio^WT and (B) Trio^cKO littermates, with binning strategy delineated by the dotted lines. C Histogram showing the distribution of GFP+ INs in the dorsal pallium of e13.5 Trio^WT and Trio^cKO brains. Histograms showing the proportion of radially migrating GFP+ cells in the dorsal pallium at e13.5 across ventro-dorsal bins (D) and in the entire neocortex (E). (n = 4 Trio^WT and 6 Trio^cKO brains). F–P Trio deletion in GABAergic INs delays tangential migration at e15.5 and induces a premature switch to radial migration mode. Examples of coronal brain sections from Trio^WT (F) and Trio^cKO (I) littermates at e15.5. High magnifications of the entry zone (G, J) and the leading edge (H, K) are shown with the delimitation between the developing neocortical layers. L–M Histograms showing the proportion of radially migrating GFP+ INs in the entire neocortex (L) and in the cortical plate (CP) only (M). Histograms showing the proportion of GFP+ INs at e15.5 across the dorsal pallium in the entry zone (N) and the leading edge (O) between Trio^WT and Trio^cKO brains. P Line graph showing the fluorescence intensity across the migratory streams at e15.5 at the neocortex entry zone (see the white dotted rectangle in inserts in F, I) between Trio^WT and Trio^cKO mice. (n = 4 Trio^WT and 3 Trio^cKO brains). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, by Mann–Whitney (E, L, M) or two-way ANOVA followed by Bonferroni’s multiple comparisons test (C, D, N, O, P). Scale bars: 200 µm (B, I) and 50 µm (K).