Background: To study normal quantitative cellular relations and the effect of optic nerve section on neurons, glia and capillaries, morphometry was carried out on 24 whole-mount retinae of 12 rats.
Methods: In the left eye the optic nerve had been sectioned 30 days before death; the right eyes served as controls. Using a cresyl violet stain, cells in the retinal ganglion cell layer were evaluated at three distances from the papilla (1.2, 2.4 and 3.6 mm).
Results: Gradients for density of neurons, glial cells and capillary grid were all within a small range (center: mid:periphery = 1.41-1.59: 1.29-1.33: 1.00). For all these distances we found a fairly constant ratio among the three histological parameters: 44.7-46.6 neurons and 2.3-2.6 glial cells were counted per capillary grid square (geometric model for the capillary meshwork). Thirty days after section of the optic nerve the capillary meshwork remained unaffected (96.2 grid squares/mm2 before nerve section vs 94.7 grid squares/mm2 after nerve section) while glial cells had more than doubled (238 vs 498 cells/mm2) and nearly half of all neurons had gone (4371 vs 2244 cells/mm2). Size characteristics of amacrine cells were similar for all three eccentricities, whereas peripheral retinal ganglion cells tended to be considerably larger than central ones.
Conclusions: Cresyl violet stain can be used to study quantitative changes of neurons, glial cells and capillary grid in the retinal ganglion layer of a single whole-mount retina. There is a remarkable degree of proportionality between the density of these cells over the whole normal retina.