Fig. 6. C3G^gt/gt mutant cortical neurons fail to migrate in ex vivo brain slice cultures. Confocal microscopy (A,B,E-K) and epifluorescence images (C,D) of wild-type (A,C,E,G) and C3G^gt/gt mutant (B,D,F,H-K) mouse forebrain slices. Brain slices were recovered at E12.5. Proliferating neural precursor cells were infected with eGFP-expressing retrovirus to mark (green) proliferating cells and their differentiating and migrating progeny. Brain slices were cultured for 48 hours and then visualised by fluorescence microscopy. (A,B) Frozen sections of brain slices counterstained with TRITC-phalloidin marking filamentous actin reveal the structure of the cortex primordium. Note that wild-type, but not C3G^gt/gt mutant, forebrain slices developed a cortical plate (A, versus arrows in B) and that wild-type (arrows in A), but not C3G^gt/gt mutant (arrowheads in B), neurons migrated away from the ventricle. Wild-type neurons exhibited long radial processes (arrowheads in E,G), whereas C3G^gt/gt mutant neurons had multiple short processes (arrowheads in D,F,H-K). For time-lapse, see Movies 1, 2 in the supplementary material. Dashed line, ventricular surface; CP, cortical plate; LV, lateral ventricle; PS, pial surface. Scale bar: 141 µm in A,B; 73 µm in C,D; 96 µm in E,F; 37 µm in G; 27 µm in H; 18 µm in I; 29 µm in J,K.