Electroporation of the superficial perinatal cortex. (A) After identifying lambda through the surface of the skull, an injection was made roughly equidistant between lambda and the eye bulge. (B) Parallel orientation of tweezertrodes for cortical electroporation (EP). Note that the positive electrode is placed on the right side of the skull to drive negatively-charged plasmid DNA in this direction. (C) Orientation of tweezertrodes for directing current toward the ventral side. (D) Maximum intensity projection of the cortical pial surface showing EGFP (green) and nuclear TagBFP (actually blue, but pseudocolored red) as imaged with a macroconfocal microscope. (E) Quantification of electroporated cells (n = 3 mouse pups each). (F) EGFP+ cells localize to the superficial layers and pial surface at 2d post-EP. Note that EGFP+ radial processes are not observed. Scale bar measures 100 μm in (F).