Indoleamine accumulating neurons in the retina of chicken and pigeon. A comparison with the dopaminergic neurons.

Recently a special group of indoleamine accumulating neurons has been described in the retina of some mammals and goldfish. These neurons are characterized by their ability to accumulate indoleamines, whereby they become visible in the fluorescence microscope. They do not show any spontaneuos fluorescence. The indoleamine accumulating neurons are in this study shown to be present in the retina of chicken and pigeon. Their cell bodies differ from the earlier described cell bodies of the same type in other species in being larger and bottle shaped instead of round or oval, and in being situated further cutwards in the inner nuclear layer. Their terminals ramify in three sublayers in the inner plexiform layer. No indoleamine containing neurons could, however, be seen to fluoresce in normal retina of chick embryos, newborn chicken, older chicken or pigeons.