CHARACTERIZATION AND ACTION OF MEIOTIC MATURATION INHIBITORS IN STARFISH OVARY

Mechanical release of oocytes from the ovary of the starfish Asterias amurensis into sea water results in spontaneous meiotic maturation of the oocytes. The substances blocking the maturation of Asterias oocytes were purified from the ovary and shown to be steroid glycosides named asterosaponins A and B. The extract prepared from isolated oocytes was incapable of inhibiting oocyte maturation. The ovarian extract inhibited the production of 1-methyladenine (1-MA) in follice cells surrounding the oocyte. The ovarian extract failed to influence 1-MA-induced maturation of the oocyte with or without follicle cells. The role the ovarian extract containing steroid glycosides was to arrest spontaneous production of 1-MA in follicle cells. The suppression could be overcome by the action of a gonadotropic peptide hormone released from the nerve tissue.