Long-term effect of retinal ganglion cell axotomy on the histomorphometry of other cells in the porcine retina.
OBJECTIVE
To determine the effect of retinal ganglion cell axotomy on the thickness of inner plexiform, inner nuclear, and outer plexiform layers, as well as the densities of short- and middle-to-long-wavelength cones, in the porcine retina.


METHODS
Unilateral retinal ganglion cell axotomy was performed in seven domestic pigs by either surgical optic nerve section or peripapillary argon laser photocoagulation. Damage to the retinal vasculature was ruled out with fluorescein angiography. Histologic examination of the retinal tissue was performed nine months later. Cone densities were determined immunohistochemically with the anti-visual pigment antibodies COS-1 and OS-2. Image analysis of semithin retinal cross sections was used to measure the thickness of the retinal layers. The effect of axotomy was quantified by optic nerve axon counts and estimations of retinal ganglion cell counts. The data were compared between the eyes with axotomy and the contralateral normal eye using the nonparametric Wilcoxon rank sum test.


RESULTS
Treatment of the peripapillary retina with the argon laser resulted in a median decrease in axon counts and retinal ganglion cell density estimates of 31%. No optic nerve axons and cells resembling retinal ganglion cells were found in the eyes with transected optic nerves. There was no significant difference in either the thickness of any retinal layers or cone densities between axotomized and normal control eyes.


CONCLUSIONS
No signs of retrograde transsynaptic degeneration were observed in porcine retinas nine months after retinal ganglion cell axotomy.
Komáromy
András M
AM
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainsville, FL 32610-0126, USA. komaromya@mail.vetmed.ufl.edu
Brooks
Dennis E
DE
Källberg
Maria E
ME
Dawson
William W
WW
Szél
Agoston
A
Lukáts
Akos
A
Samuelson
Don A
DA
Sapp
Harold L
HL
Gelatt
Kirk N
KN
Sherwood
Mark B
MB
D000818:Animals; D019771:Axotomy; D002452:Cell Count; D005451:Fluorescein Angiography; D007150:Immunohistochemistry; D017075:Laser Coagulation; D020221:Optic Nerve Injuries; D012160:Retina / Q000473:pathology* / Q000601:surgery*; D017949:Retinal Cone Photoreceptor Cells / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000473:pathology; D013552:Swine; D013997:Time Factors