Retinal ganglion cell population in adult albino and pigmented mice: a computerized analysis of the entire population and its spatial distribution.
In adult Swiss albino and C57 pigmented mice, RGCs were identified with a retrogradely transported neuronal tracer applied to both optic nerves (ON) or superior colliculi (SCi). After histological processing, the retinas were prepared as whole-mounts, examined and photographed under a fluorescence microscope equipped with a motorized stage controlled by a commercial computer image analysis system: Image-Pro Plus((R)) (IPP). Retinas were imaged as a stack of 24-bit color images (140 frames per retina) using IPP with the Scope-Pro plug-in 5.0 and the images montaged to create a high-resolution composite of the retinal whole-mount when required. Single images were also processed by specific macros written in IPP that apply a sequence of filters and transformations in order to separate individual cells for automatic counting. Cell counts were later transferred to a spreadsheet for statistical analysis and used to generate a RGC density map for each retina.


RESULTS
The mean total numbers of RGCs labeled from the ON, in Swiss (49,493+/-3936; n=18) or C57 mice (42,658+/-1540; n=10) were slightly higher than the mean numbers of RGCs labeled from the SCi, in Swiss (48,733+/-3954; n=43) or C57 mice (41,192+/-2821; n=42), respectively. RGCs were distributed throughout the retina and density maps revealed a horizontal region in the superior retina near the optic disk with highest RGC densities. In conclusion, the population of mice RGCs may be counted automatically with a level of confidence comparable to manual counts. The distribution of RGCs adopts a form of regional specialization that resembles a horizontal visual streak.
Salinas-Navarro
M
M
Laboratorio de Oftalmología Experimental, Facultad de Medicina, Universidad de Murcia, E-30100 Murcia, Spain.
Jiménez-López
M
M
Valiente-Soriano
F J
FJ
Alarcón-Martínez
L
L
Avilés-Trigueros
M
M
Mayor
S
S
Holmes
T
T
Lund
R D
RD
Villegas-Pérez
M P
MP
Vidal-Sanz
M
M
D016117:Albinism, Ocular / Q000473:pathology*; D000818:Animals; D002452:Cell Count; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D009900:Optic Nerve / Q000166:cytology / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000473:pathology*; D013477:Superior Colliculi / Q000166:cytology / Q000473:pathology