The development of tubular heart in RNA-treated post-nodal pieces of chick blastoderm.

Post-nodal pieces of the stage-4 chick blastoderms were transected 0-6 mm posterior to Hensen's node and cultured in vitro with and without chicken-heart RNA. After 24 h the explants were fed daily with fresh egg-extract medium for 4 days. On the 4th day pulsating heart was found in the RNA-treated but not in the untreated series. Histological examination revealed that cell differentiation other than of erythrocytes and epithelial tissue seldom occurred in the control and, in contrast, pulsating heart and cardiac myoblasts were present in most of the RNA-treated explants that had differentiated.