Electroporation efficiency using electrodes of different sizes. (A) Schematic representation of the position and size (10 mm and 5 mm) of the electrodes used in the first part of this study. Only the positive pole is represented. (B) Representative example of electroporated radial glial cells (RGCs) expressing high levels of GFP at 1 day post-electroporation. The right panel shows a higher magnification of the region surrounded by the dotted box. Only cells with clear RGC morphology, that is, with an end foot contacting the ventricle surface and a main apical process, were counted. DAPI (blue) was used as a nuclear counterstain. (C,D) Measurements of the electroporated area (C) and of the number of electroporated RGCs (D) when 10-mm (filled bar) or 5-mm (hatched bars) diameter electrodes were used. Please refer to Materials and methods and Additional file 1 for experimental details. Note that the use of smaller electrodes does not improve the precision of electroporation (that is, did not decrease the electroporated area size), but tend to decrease the number of electroporated cells. Error bars represent standard error of the mean. Scale bars: 50 μm and 10 μm in (B) (left and right panels, respectively). LV, lateral ventricle.