Dopamine was not the first substance presumed to be a neurotransmitter in the retina, but today it is probably the best proven. The first indication of this role was obtained in 1963. With the aid of the formaldehyde histofluorescence method of FALCK and HILLARP it was shown that the formaldehyde treatment induced fluorescence in certain neurons of the retina, indicating that they contain a catecholamine which was later shown to be dopamine (Table I). The dopamine containing cell bodies were found among the amacrine cells (Fig. 1) and their processes distribute in one to three sublayers in the inner plexiform layer, depending on the animal species. Figure 2 summarizes data from the literature (1–15). These cells were named junctional cells, and, as will be discussed below, they are most likely dopaminergic, i.e. their transmitter is dopamine. The number of these cells has never been accurately assessed, but they can be estimated to constitute a few per cent of the amacrine cell bodies. As will be discussed below, they have the type of synapse ascribed to amacrine cells and may thus be regarded as a subpopulation of amacrine neurons. Further, a few dopaminergic cell bodies can be found in the inner plexiform layer and among the ganglion cells. Their branches are found in the inner plexiform layer, mixing indistinguishably with the processes of the dopaminergic junctional cells. The dopaminergic neurons among the ganglion cells are few, only a few per cent of the number of junctional cells. They have been called alloganglion cells. The dopaminergic neurons in the inner plexiform layer are fewer still, and have been called eremite cells. Since the detailed morphology of the branches of these cells is unknown and also which contacts they make with other cells it is not possible to tell whether they represent special classes of cells. The simplest explanation is that they are displaced dopaminergic junctional cells. Neither the alloganglion cells nor the other dopaminergic neurons have been found to send axons to the optic nerve (16) and are therefore entirely intraretinal.