A new technique for dechorionation and observations on the development of the naked egg in Oryzias latipes

A simple technique for removing the chorion (egg envelope) of Oryzias latipes eggs is described in which the chorion is mechanically cut off with microsurgical scissors before and immediately after insemination. When dechorionated eggs were inseminated, a high incidence of polyspermic fertilization was observed. Fusion was induced among dechorionated eggs that were in contact when they were inseminated with a high concentration of spermatozoa. However, monospermic eggs that were dechorionated immediately after completion of the cortical reaction induced by insemination changed shape periodically during cleavage and developed normally to fry.