Fig. 6. Switch from tangential to radial position during CP invasion is perturbed after addition of Y27632. (A) Schematic showing the preferential orientation of interneurons in the cortex at E15.5 and after 48 hours in culture. Interneurons invade the CP performing a rapid change in direction (Ang et al., 2003; Polleux et al., 2002). (B-D) Images of cortical slices at E15.5 (B) or after 48 hours in culture (C,D) showing the distribution of GFP/BrdU+ interneurons, treated with vehicle (C) or Y27632 (D). Solid and open arrowheads indicate tangentially and radially oriented cells, respectively. (E) Quantification of percentage of GFP/BrdU+ radially and tangentially oriented neurons in control and Y27632-treated slices after 48 hours in culture. Bars show mean±s.e.m. Control: 41.99±5.37% (radially oriented), 58.00±6.02% (tangentially oriented), n=231 cells from four slices of two independent experiments; Y27632: 23.21±2.42% (radially oriented), 76.79±2.42% (tangentially oriented), n=280 cells from four slices of two independent experiments. ²-test, ^***P<0.001, ^**P<0.01. (F) Schematic showing the criteria for the classification of the orientation of interneurons in cortical slices. (G,H) Schematic representation of the distribution of GFP/BrdU+ interneurons in C and D, respectively. Solid and open arrowheads indicate tangentially and radially oriented cells, respectively. Scale bar: 100 µm.