Morphometric examination of human and monkey retinal ganglion cells within the papillomacular area.
OBJECTIVE
To examine the morphology of the retinal ganglion cells (RGCs) in the lesser characterized area lying between the optic disk and the macula that consists of the central papillomacular area (PMA) and the arcuate papillomacular bundle (PMB).


METHODS
Nineteen human and 10 monkey (Macaca fascicularis) retinas obtained after death were used in the study. Perikaryal, axonal, and dendritic silhouettes were examined by postvital application of the fluorescent dye DiI, which specifically labeled RGCs when placed onto the optic fiber layer. The retinas were freed from surrounding tissue, prepared as flat mounts on a nitrocellulose filter, and fixed overnight in 4% paraformaldehyde. DiI diffuses along the membranes of ganglion cell axons, thereby completely labeling them, their cell bodies, and dendrites, which enables the RGCs to be examined with fluorescence microscopy.


RESULTS
In both species, midget cells represented most of the RGCs within the PMA (96.15%) and possessed small, umbrella-like dendrites oriented toward the deeper retinal layers. Parasol cells were less abundant in both species and had small, typical symmetric dendrites. Also along the PMB, midget cells represented most cells (91.52%), whereas only 8.47% could be categorized as parasol cells. In both species, parasol cells of the PMB extended dendrites, which were oriented perpendicular to the axons.


CONCLUSIONS
The data show that the PMA and PMB mainly contain small midget cells of typical morphology and size but with atypically oriented dendrites, which are only characteristic for this retinal area.
Pavlidis
Mitrofanis
M
Department of Experimental Ophthalmology, School of Medicine, University Eye Hospital Münster, Domagkstrasse 15, D-48149 Münster, Germany.
Stupp
Tobias
T
Hummeke
Markus
M
Thanos
Solon
S
D000368:Aged; D000818:Animals; D001369:Axons / Q000502:physiology; D002232:Carbocyanines; D002452:Cell Count; D003712:Dendrites / Q000502:physiology; D005456:Fluorescent Dyes; D006801:Humans; D008252:Macaca fascicularis; D008266:Macula Lutea / Q000033:anatomy & histology*; D008875:Middle Aged; D009898:Optic Disk / Q000033:anatomy & histology*; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000502:physiology
D002232:Carbocyanines; D005456:Fluorescent Dyes; C024286:3,3'-dioctadecylindocarbocyanine