NITRIC-OXIDE SYNTHASE IN CHICK-EMBRYO RETINA DURING DEVELOPMENT

High levels of nitric oxide synthase were found in the early stages of developing chick embryo retina, The enzyme activity sharply decreased up to 13-day-old chick embryo retina, when the level of the last embr yonic day was reached, The results show that nitric oxide is synthesiz ed in chick embryo retina prior to synaptogenesis. The incubation of c hick embryo retinas in presence of NMDA increased the synthesis of nit ric oxide, thus, the appearance of nitric oxide production before the synaptogenesis in the retina as well as in the brain may be considered as signal for the development and shaping of neuronal and non-neurona l cells.