VISUALIZATION OF HUMAN CHOROIDAL GANGLION-CELLS WITH THE SUPRAVITAL FLUORESCENT DYE 4-(4-DIETHYLAMINOSTYRYL)-N-METHYLPYRIDIUM IODIDE

The distribution and morphology of ganglion cell bodies and nerve fibe rs in supravital human choroidea is studied by staining with the fluor escent dye 4-(4- diethylaminostyryl)-N-methylpyridium iodide (4-Di-2-A SP). We have used the choroids from human donor eyes donated for corne a transplantation. The isolated tissues were rinsed in ringer solution and processed within up to 24 h after death with 3 mu M of 4-Di-2-ASP in Ringer for 5-60 min at different temperatures (4-37 degrees C). Af ter incubation, choroid whole flat mounts were observed in a fluoresce nce microscope. A delicate network of nerve fibers could be distinguis hed as soon as 5 min after immersion in 4-Di-2-ASP. In addition, label led ganglion cell perikarya could be seen after longer incubation peri ods. They occurred individually or grouped in small ganglia of up to 8 cells and were linked together by various processes, which could also be traced to blood vessels. The fluorescent dye 4-Di-2-ASP provides a quick and simple method to visualize the innervation of the human cho roid, including local ganglion cells. This nontoxic fluorescent techni que will permit further manipulation and electrophysiological investig ation of choroidal innervation.