RESUMO
The effect of conditioned medium from aggregates of chick embryo retinal cells was tested on the in vitro survival of retinal ganglion cells were identified by the detection of retrogradely transported horseradish peroxidase injected bilateral into the superior colliculus. Culture medium conditioned with chick embryo retinae was tested on monolayers of rat retinal cells with plating densities ranging from 0.5 to 4 x 10 5 cells/cm2. In all cases the conditioned medium significantly increased the survival of ganglion cells after 2 days in culture. Conditioned media from embryonic days 8 to 16 (E8 to E16) presented neurotrophic activity, with the greatest effect occurring at E10-E12. The conditioned medium had no effect on the adhesion of rat retinal cells. The data suggest that chick retinal cells produce soluble trophic factors which can influence the survivalof rat retinal ganglion cells in vitro. Furthermore, the release of this neurotrophic activity by chick retina seems to be developmentally regulated