Fig. 1

a Immunostaining against choline acetyltransferase (ChAT) in cross-sections of human retina. Two types of ChAT-positive cells can be observed: bright (arrowheads) and dim (arrows). b Immunostaining against parvalbumin (PV, in red) and choline acetyl transferase (ChAT, in green) in the human retina. c, d Details of the ChAT-positive cells in the inner nuclear layer (INL). Bright ChAT-positive cells (arrowhead) are also parvalbumin-positive, and dim ChAT-positive cells (arrow) are parvalbumin-negative. e Immunostaining against ChAT (green) and calbindin (red) in the human retina. f, g Details of the ChAT-positive cells in the INL and the ganglion cell layer (GCL). f Thin processes (blue arrowheads) of dim ChAT-positive cells (arrow) stratify in strata 3 and 4 (S3/S4, blue arrowheads). g Bright ChAT-positive cells (arrowhead) are also calbindin-positive, and dim ChAT-positive cells (arrow) are calbindin-negative. h–j Immunostainings against ChAT (red) and glycine (green) in the human retina. Bright ChAT-positive cells (arrowheads) are glycine-negative, and dim ChAT-positive cells (arrow) are also glycine-positive. k–m Immunostainings against ChAT (red) and GABA (green) in the human retina. Bright ChAT-positive cells (arrowheads) are also GABA-positive, and dim ChAT-positive cells (arrows) are GABA-negative. S2: stratum 2 in the inner plexiform layer (IPL), S4: stratum 4 in the IPL, OPL: outer plexiform layer, NFL: nerve fiber layer. Scale bars: 20 μm (a–d; i–m), 15 μm (e–h)