Ultrastructural study of the spermatogenesis and mature spermatozoa ofDicrocoelium dendriticum (Plathelminthes, Digenea)

Abstract

The spermatogenesis and spermatozoon of Dicrocoelium dendriticum were studied by transmission electron microscopy. Peripheric accessory cells project between germ cells. Each spermatogonium gives rise to 32 spermatozoa. The stages in spermiogenesis include development of the zone of differentiation, appearance of the intercentriolar body flanked by two centrioles from each of which a free axoneme and a striated rootlet grow, outgrowth of the differentiation zone to form the median cytoplasmic process and migration of the nucleus and mitochondria into it, and rotation of the flagella and subsequent proximodistal fusion of the three projections to form a monopartite spermatozoon. The spermatozoon possess two incorporated axonemes with the "9 + 1" pattern typical of those in trepaxonematid plathelminths. beta-Glycogen particles accumulate in the spermatozoa after they have separated from the cytophore as revealed by Thiery's method. This study confirms in a further family, Dicrocoeliidae, the constant pattern of spermiogenesis and spermatozoon structure in Digenea.

Spermiogenesis and sperm ultrastructure of Carmyerius endopapillatus (Digenea, Gastrothylacidae), a parasite of Bos taurus in Senegal

“…The flagella of the first four species have the particularity of a rotation of 120° before fusion with the median cytoplasmic expansion. This fusion in C. endopapillatus is proximo-distal as it is in all the studied trematodes (Cifrian et al 1993;Miquel et al 2000;Ndiaye et al 2002;Levron et al 2003Levron et al , 2004aSeck et al 2007). The fusion of plasmic membranes begins near the cytoplasmic mass and ends at the distal extremity of the old spermatid.…”

Dicrocoelium hospes Looss, 1907 (Digenea, Dicrocoeliidae): spermiogenesis, mature spermatozoon and ultrastructural comparative study

“…gigantica, Ndiaye et al 2004; Monorchis parvus, Levron et al 2004). Furthermore, in D. hospes migration of the nucleus and mitochondria occurs before the fusion of the first flagellum unlike the results concerning D. dendriticum spermiogenesis (Cifrian et al 1993) where the nucleus migrates after the proximodistal fusion and also unlike the results concerning S. palaearcticum (Ndiaye et al 2002) and N. neyrai (Ndiaye et al 2003b) where the mitochondrion migrates after the proximodistal fusion. Our results corroborate those of Burton (1972), who suggested that nuclear migration is necessary for the fusion of the median process with flagella, and also that the nucleus is always present when fusion occurs.…”

“…However, relatively few ultrastructural investigations have been made on spermatogenesis and spermatozoon in Dicrocoeliidae digeneans. These referred to D. dendriticum (Morseth 1969;Cifrian et al 1993), Eurytrema pancreaticum (Fujino et al 1977), Corrigia vitta (Robinson and Halton 1982) and D. chinensis (Tang 1996). The family Dicrocoeliidae Odhner, 1910 contains species with a noticeable human and veterinary interest (Mas-Coma and Bargues 1997).…”

Spermiogenesis and ultrastructure of the spermatozoon of Wardula capitellata (Digenea, Mesometridae), an intestinal parasite of the sparid teleost Sarpa salpa in Senegal

“…Moreover, in several sections during the final stages of spermiogenesis, the mitochondrion is observed in migration. Contrarily, a mitochondrial migration before nuclear migration has been reported in the spermiogenesis of Dicrocoelium dendriticum (Cifrian et al 1993), Postorchigenes gymnesicus (Gracenea et al 1997) and R. exasperatum (Bakhoum et al 2011b).…”