In vitro Production of Meiosis Inducing Substance by Nerve Extract in Ovary of Starfish

Abstract

IT is well known that spawning can be induced by injecting a water extract of radial nerves into the coelomic cavity of mature male or female starfish^1–4. The coelomic fluid of the starfish, Asterias amurensis, at the time of natural spawning shows gamete shedding activity similar to that of nerve extracts, and so the active substance seems to be liberated from nerve into the coelomic cavity, where the gonads are suspended⁵. This gamete shedding substance is a polypeptide^3,6 and seems to be a neurosecretory substance^3,7. As well as inducing spawning, it may act directly on the ovary and induce oocyte maturation^7,8, for in A. amurensis local application of nerve extract to an isolated ovary induces maturation of oocytes located only in the treated portion, and isolated oocytes in calcium free sea water containing nerve extract undergo meiosis⁸. Oocytes of A. amurensis usually undergo meiosis when isolated in normal sea water but not in calcium free sea water.