The shapes and numbers of amacrine cells: Matching of photofilled with Golgi-stained cells in the rabbit retina and comparison with other mammalian species

Amacrine cells of the rabbit retina were studied by "photofilling," a photo chemical method in which a fluorescent product is created within an individ ual cell by focal irradiation of the nucleus; and by Golgi impregnation. Th e photofilling method is quantitative, allowing an estimate of the frequenc y of the cells. The Golgi method shows their morphology in better detail. T he photofilled sample consisted of 261 cells that were imaged digitally in through-focus series from a previous study (MacNeil and Masland [1998] Neur on 20:971-982). The Golgi material consisted of 49 retinas that were staine d as wholemounts. Eleven of these subsequently were cut in vertical section . Of the many hundreds of cells stained, digital through-focus series were recorded for 208 of the Golgi-impregnated cells. The two methods were found to confirm one another: Most cells revealed by photofilling were recognize d easily by Golgi staining, and vice versa. The greater resolution of the G olgi method allowed a more precise description of the cells and several typ es of amacrine cell were redefined. Two new types were identified. The two methods, taken together, provide an essentially complete accounting of the populations of amacrine cells present in the rabbit retina. Many of them co rrespond to amacrine cells that have been described in other mammalian spec ies, and these homologies are reviewed. (C) 1999 Wiley-Liss, Inc.