Postmortem preservation of ganglion cells in the human retina. A morphometric investigation with the carbocyanine dye DiI.

Postmortem morphometric investigation of autopsy material is helpful for understanding the alterations cells undergo during life. The present work was undertaken to determine the morphologic features of human retinal ganglion cells during the first 2 days after death. Ganglion cells of 16 retinas were obtained from eyes, the corneas of which had been retrieved for keratoplasties. The ganglion cells were stained with the fluorescent carbocyanine dye Dil and investigated 12 to 36 hours postmortem. All labeled cells identified as ganglion cells had well preserved, type-specific dendritic profiles that made it possible to catalog them according to the established classes of ganglion cells. The various types of cells have in common some typical morphologic changes that occur during the postmortem period of observation: swelling and varicosity in the cell bodies and along the dendritic branches and the axons. These swellings were consistent throughout the postmortem period and did not hinder the identification of particular types of ganglion cells. The two major types (parasol and midget) and various subtypes of ganglion cells were identified morphologically. There are two distinct morphologic types of midget cells which differ from each other in the pattern of dendritic branching. Particular emphasis was given to analyze the dendritic geometry of the large parasol cells. A new finding in the human retina is the frequent presence of large parasol ganglion cells, the axons of which course along aberrant intraretinal paths, especially in the extreme periphery of the retina.