Characteristics of differentiation and development of neurons and glial cells of the neural retina and the retinal pigment epithelium are studied in cultured cells and in freshly dissected tissues. The primary model used is a human retinoblastoma cell line (Y-79) maintained in our laboratory. 1. These primitive neuroblasts can be induced to differentiate into cells of neuronal or glial characteristics. 2. Insulin receptors have been characterized on these cells. 3. A distinct Beta-adrenergic receptor is also present that is linked to adenylate cyclase. 4. Also the differentiating agent butyrate can induce high levels in Interphotoreceptor Retinoid-Binding Protein making it probable that the retinoblastoma cells can take on photoreceptor-like characteristics. 5. Laminin treatment of the retinoblastoma cells allows for cell adhesion and also results in marked cell differentiation.