Fig. 4

a–l Immunostaining against tyrosine hydroxylase (TH, red) and choline acetyltransferase (ChAT, green) in a section of the human retina showing examples of connections between ChAT-positive cells and TH-positive cells at the level of S1/S2 (a–f, arrowheads) and at the level of S3/S4 (g–l, arrowheads) in the IPL. m–o Retinal sections immunostained against TH (red), ChAT (green) and vesicular monoamine transporter 2 (VMAT2, blue). p–a’ Examples of connections between ChAT-positive cell somata (p–u, arrowheads) and dendrites (v–a’, arrowheads) with dopaminergic cell dendrites (TH, red) containing VMAT2 (blue). S1/S2: stratum 1 and 2 in the IPL. S3/S4: stratum 3 and 4 in the IPL. Scale bars: 2.5 μm (a–l). 20 μm (m–o). 5 μm (p–a’)