Absence of the Leydig Organ in the Esophagus of Freshwater Stingrays

Abstract

The Leydig organ, one of the hemopoietic organs of elasmobranchs, is present in the esophagus of dasyatid stingray Dasyatis akajei. However, this organ could not be detected in the South American freshwater stingrays Potamotrygon spp. This histological examination was made on all the serial esophageal sections prepared from six specimens of the freshwater stingrays. In spite of detailed investigation, the Leydig organ could not be detected in the submucous connective tissue of esophagus. Thus, absence of the Leydig organ in the South American freshwater stingrays related closely to the dasyatid stingray is very interesting from the taxonomic point of view.