Resumption of meiosis in starfish oocytes is induced by 1-methyladenine (1-MeAde) produced by ovarian follicle cells under the influence of a gonad-stimulating substance (GSS). With respect to 1-MeAde production by follicle cells of the starfish,Asterina pectinifera, (1) the action of GSS is initiated by a receptor mediated activation of G-proteins, resulting in the activation of adenylate cyclase and cyclic AMP (cAMP) formation; (2) 1-MeAde produced under the influence of GSS is not prestored within the follicle cells but is newly synthesized from a 1-MeAde precursor; (3) AMP plays an important role in the process of methylation during 1-MeAde biosynthesis induced by GSS.