A-D, Upper panels show confocal projection images indicating the extent of axonal arbors in RFP(+) hippocampal chandelier cells (h-ChCs) (A, C) and RFP(+) neocortical chandelier cells (nc-ChCs) (B, D). The A-P (A, B) and M-L (C, D) extent of ChC axonal arbors in sagittal and coronal sections, respectively, are shown. Asterisks indicate both ends of axonal arbors. Confocal single optical sections in lower right panels represent enlarged images of boxed areas in upper panels showing axonal varicosities (magenta) aligned along the axon initial segments (green) stained with anti-Ankyrin G antibodies. Lower left panels show individual cartridge structures. E, F, 3-D reconstructions of an h-ChC (E) and an nc-ChC (F) in sagittal sections. Axonal processes are color-coded according to their depth.