Landolt's club in the amphibian retina: a Golgi and electron microscope study.

Landolt's club process has been studied in the adult newt retina. In Golgi preparations this process has been shown to arise from the dendritic trunk of a bipolar cell and, to pass through the external synaptic layer without discernible synapse, apparently to terminate as an enlarged, bulb at the level of the external junctional zone (external limiting membrane). This confirms Landolt's original observations. The electron microscope reveals, in addition, that this process open lacks intervening glia between its own cell membrane and that of adjacent photoreceptors. Morphologically the club process differs somewhat from a typical dendrite. The process passes through the external junctional zone and terminates as a 9+0 cilium which extends between the receptor inner segments.