An ultrastructural and histochemical study of the germinal cells contained in hemispermatophores of males of the Aristaeomorpha foliacea (Risso, 1827)

The ultrastructure and the oligosaccharide sequence of glycoconjugates of spermatozoa contained in the hemispermatophores of males Aristaeomorpha foliacea collected during the main mating and reproductive periods have been investigated. The hemispermatophores from eleven specimens were packed with typical round-shaped spermatozoa (max ø 3.8±0.03 lm), characterised by an electron-lucent nucleus not separated by the nuclear envelope from the thin electron-dense peripheral band of the cytoplasm containing small vesicles and large mitochondria. Hemispermatophores from two out of eight specimens collected in April contained few typical spermatozoa, whereas they were filled with roundish large germinal cells (max ø 5.74±0.16 lm) showing a filamentous chromatin in the nuclear region and the cytoplasm rim rich in large vesicles and myelin-like bodies. These cells were considered as non-mature germ cells, and consequently we defined their hemispermatophores as ‘‘immature’’. The lectin histochemistry showed differences in the glycoconjugate composition between germ cells contained in immature hemispermatophores and spermatozoa. The former had N-linked oligosaccharides containing a-D-Man and internal b-D-GlcNAc (Con A and KOH-sialidase-WGA affinity) as well as terminal NeuAca2,6Gal/GalNAc and NeuAca2,3Galb1, 4-GlcNAc (SNA and MAA binding). Spermatozoa from mature hemispermatophores also displayed Olinked oligosaccharides which terminated with b-D-Gal(1–3)-GalNAc dimer (PNA binding) and aGalNAc (HPA reactivity) in the cytoplasm and with sialic acid linked to b-D-Gal(1–3)-GalNAc (KOH-sialidase- PNA procedure) in the nucleus. The extracellular matrix in immature hemispermatophores displayed both N- and O-linked glycoconjugates, whereas it contained only O-linked oligosaccharides in mature ones. Although the number of specimens examined is low, this study should indicate that the presence of hemispermatophores in the terminal ampullae of male A. foliacea and of joined hemipetasmas is not synonymous with maturity.