QUANTITATIVE RELATIONS IN THE RETINAL GANGLION-CELL LAYER OF THE RAT - NEURONS, GLIA AND CAPILLARIES BEFORE AND AFTER OPTIC-NERVE SECTION

Background: To study normal quantitative cellular relations and the ef fect of optic nerve section on neurons, glia and capillaries, morphome try 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 f rom 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 ran ge (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 histologic al 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/mm(2) before nerve section vs 9 4.7 grid squares/mm(2) after nerve section) while glial cells had more than doubled (238 vs 498 cells/mm(2)) and nearly half of all neurons had gone (4371 vs 2244 cells/mm(2)). Size characteristics of amacrine cells were similar for all three eccentricities, whereas peripheral re tinal ganglion cells tended to be considerably larger than central one s. Conclusions: Cresyl violet stain can be used to study quantitative changes of neurons, glial cells and capillary grid in the retinal gang lion layer of a single whole-mount retina. There is a remarkable degre e of proportionality between the density of these cells over the whole normal retina.