Fig. 31 Summary of the neural elements and their neurotransmitter assignments in the five strata of a typical vertebrate inner plexiform layer (IPL). Amacrine cell bodies (AC) are at the top and the ganglion cells (GC) are at the bottom of the image. To the right is shown the five strata of the IPL in the micrograph and the types of processes that are found within these strata. S1 and S2 are OFF center strata where OFF center bipolar axons (OFF BCs) and OFF center ganglion cell dendrites (OFF GCs) make contact. The inner three strata 3–5 are ON center and contain axons and dendrites of bipolar and ganglion cells respectively (ON BCs, ON GCs). OFF acetylcholine-containing amacrine cells (OFF ACh AC) and ON Ach AC are shown in pink plexi of processes. Putative glycinergic amacrine dendrites are larger lobular processes colored green, occurring throughout the IPL. GABA-IR dendrites are usually arranged in thinner wide-ranging profiles and enlarged beads are bipolar terminals (yellow profiles). Typically ON-OFF ACs are found at the borders of ON and OFF strata and are GABAergic dendrites. Other neurochemical substances contained in various amacrine cell dendrites are shown. (Kolb H, Nelson R, Ahnelt P et al: Cellular organization of the vertebrate retina. In Kolb H, Ripps H, Wu S (eds): Progress in Brain Research, Vol. 131. Amsterdam: Elsevier Science BV, 2001:3–26)