On te Ldydig Organ in the Esophagus of Some Elasmobranchs

Abstract

The Leydig organ is, in addition to spleen and epigonal organ, the third hemopoietic organ of elasmobranchs, and located in the submucosal layer of esophagus. Recently, however, absence of this organ was reported in the Atlantic nurse shark Ginglymostoma cirratum, the California hornshark Heterodontus francisci, and a few other species. So, the present study inverstigated whether the organ was detectable or not in three elasmobranch species; Dochizame Triakis scyllia, Hirataei Urolophus aurantiacus, and Nekozame Heterodontus japonicus. The result of examination revealed that the Leydig organ is present in the esophagus of T. scyllia and U. aurantiacus, but absent in that of H. japonicus as in H. francisci.