FINE STRUCTURAL OBSERVATIONS ON NUAGE-LIKE STRUCTURES DURING SPERMATOGENESIS OF BRANCHIPUS VISNYAI (CRUSTACEA: ANOSTRACA)

Abstract

An electron-dense fibrogranular nuage-like structure appears in primary spermatocytes of Branchipus visnyai. In spermatids, in addition to mitochondria and a Golgi complex, it is closely associated with a cluster of small electron-opaque granules probably derived from itself. Subsequently the small granules fuse together forming another large amorphous granule. The significance of these structures is at present unknown. Many investigators have reported that during the gametogenesis of different animal groups, the germinal cells contain one or more densely staining bodies located in the perinuclear cytoplasm which probably are derived from nuclear material (see Eddy, 1975, for a review). These structures, which seem to be a common feature ofgerminal cells, have been given a variety of names. A frequently used term is nuage, originally employed by Andre and Roullier (1957). As far as the function of the nuage is concerned, it has been suggested that it might correspond to the germ plasm in several animals or it might represent a reserve of ribonucleoproteins that is used in later stages for ribosomal maturation (Eddy, 1974, 1975; Kellokumpu-Lehtinen and S6derstr6m, 1978; Azevedo, 1984). However, the definite function of the nuage remains in question, and we cannot exclude that the morphologically similar nuage observed in different animal germ cells might correspond to functionally different structures. In this paper we report some fine structural observations on nuage-like structures during the spermatogenesis of Branchipus visnyai. This is the first report on the presence of nuage-like structures in anostracan germ cells.