QUANTITATIVE AND TOPOGRAPHICAL STUDY OF RETINAL GANGLION-CELLS IN THECHAMELEON (CHAMELEO CHAMELEON)

Chameleons display a number of well-described physiological peculiarit ies of their visual system, but there is no information on the topogra phy of the retinal ganglion cell layer, In the present study, ganglion cell density of the chameleon retina was constructed from whole mount s of the retina stained with cresyl violet, For the identification of ganglion cells, these latter cells were labelled retrogradely with hor seradish peroxidase applied to the optic nerve, Using this criterion, the proportion of ganglion cells was estimated to represent 80% of ret inal cells, while glial cells and amacrine cells represented 14 and 6% , respectively, of the total cell population of the retina. As for the main features of the retinal map, first, ganglion cells were distribu ted inhomogeneously within the ganglion cell layer, and revealed the e xistence of a putative area centralis. Second, a horizontal visual str eak, which showed two peak density areas, was identified. These featur es point out the degree of specialisation of the chameleon retina and the complexity of its visual system. (C) 1997 Elsevier Science Inc.