Examines the role of exogenous purine nucleosides for the growing oocytes of Nereidid polychaetae Nereis virens. Gamete development in Nereis virens and other nereidid polychaetes; Supply of purine nucleosides by eleocytes which is a coelomic cell type to support nucleic acid synthesis in the oocytes; Intake of inosine and guanosine by oocytes.