Abstract:Water-extracts of radial nerves from the starfish and dithiothreitol (DTT) were used to induce the oocyte maturation of the sea cucumber Apostichopus japonicus (slenka). Although radial nerve extracts failed to induce oocyte maturation in the sea cucumber, breakdown of germinal vesicles and subsequent meiotic behavior of chromosomes were induced by the treatment with DTT. Oocytes of the sea cucumber A. japonicus are arrested at the germinal vesicle (GV) stage and do not start maturation spontaneously, after being treated with DTT for 20 min, the GV begins to migrate to the animal pole of the oocyte, then the GV breaks down, that is called germinal vesicle breakdown (GVBD). Meiosis of the oocyte reinitiated and two polar bodies protrude out successively. DTT with the condensation of 10-1 mol/L to 10-5 mol/L can successfully induce GVBD. Maturation ratio can reach to 90% when the condensation of the DTT solution is 10-2 mol/L, oocytes induced to maturation can be fertilized, while they can not develop normally.
