A Spontaneous Hermaphrodite of the Japanese Eel, Anguilla japonica, and Its Artificial Maturation

Abstract

A spontaneous hermaphrodite was found out among a group of silver females of the Japanese eel, Anguilla japonica, collected in Aomori Prefecture, Japan.The hermaphroditic gonad was predominantly ovarian in anatomical and histological aspects, but was provided with numerous, discrete masses of testicular tissue of normal histoarchitecture which were localized along the distal edge of the gonad.The hermaphrodite was subjected to weekly injections of HCG followed by salmon pituitaries in an attempt to induce sexual maturation of the gonad.Successive biopsies of the gonad carried out before and during the hormonal treatment confirmed that both the testicular and the ovarian portions of the hermaphroditic gonad could rapidly develop into full maturation in response to the exogenous gonadotropins.