Melano-macrophage centres in the gonads of the swamp eel, Synbranchus marmoratus Bloch, (Pisces, Synbranchidae): histological and histochemical characterization

Abstract. During a study of the gametogenesis of the swamp eel. Synbranchus marmoratus Bloch, conspicuous structures were found randomly distributed among the germinal cells and gonadal stroma. At low magnification, these structures appeared as yellowish to dark spherical bodies. Histological and histochemical examination showed clusters of cells with generally pyknotic nuclei and cytoplasm containing lipofusein-like substances. A comparison of these structures with the melano-macrophage centres (MMCs) present in the liver and spleen, showed the same structure and features. Their presence and function in the gonads of S. marmoratus might be related not only with the basic functions of the MMCs, but also with the degradation of atretic and/or non-ovulated follicules, principally during the post-spawning period.