Abstract: The results of several studies have demonstrated that cell differentiation influenced by derivatives of retinoic acid. To determine whether retinoic acid mediate the differentiation of neural stem cells we treated dissociated hippocampal stem cells with different concentrations of all trans or 9-cis retinoic acid and analyzed the effects on cell fate by specific monoclonal antibody for photoreceptors. Addition of exogenous retinoic acid caused a dose dependent specific in the elevation of the cell number that developed as photoreceptors in culture. Also results of immunohistochemical studies using monoclonal antibody demonstrated that the primary effect of retinoic acid was to influence progenitor cells the developed as mature and immature photoreceptors. These results suggest that retinoic acid may play an important effect in the normal development of photoreceptor cells in vitro.