Spermatogenesis and Spermiogenesis in Didymocystis wedli Ariola, 1902 (Didymozoidae, Digenea)

Vol. 96(8): 1153-1159, November 2001

MC Pamplona-Basilio⁺, MFD Baptista-Farias, A Kohn⁺⁺

Laboratório de Helmintos Parasitos de Peixes, Departamento de Helmintologia, Instituto Oswaldo Cruz-Fiocruz, Av. Brasil 4365, 21045-900 Rio de Janeiro, RJ, Brasil

The ultrastructure of the male reproductive system of Didymocystis wedli was studied for the first time, demonstrating spermiogenesis and spermatogenesis at different cell stages. The spermatozoa morphology was compared with that of other Digenea species.

It was observed that the different cells of the spermatogenesis process follow the classic pattern reported for the majority of the parasitic platyhelminthes. During spermiogenesis, rootlet fibers, electrondense bodies and median cytoplasmic process were not observed. The mature spermatozoa of D. wedli were filiform, presenting nucleus, mitochondrion and two 9+1 axonemes, with a biflagellate distal extremity.

Key words: spermatogenesis - spermiogenesis - Digenea - Didymocystis wedli

The ultrastructure of spermiogenesis and spermatozoon have previously been used as characters for phylogenetic studies within the Platyhelminthes (Justine 1991, 1995).

Indeed spermatogenesis of Digenea has been the subject of several studies in recently published papers, although these dealt with only a few of the existing species, such as Mesocoelium monas by Iomini et al. (1997), Echinostoma caproni by Iomini and Justine (1997), Postorchigenes gymnesicus by Gracenea et al. (1997), and Sac-cocoelioides godoyi by Baptista-Farias et al. (2000). In the family Didymozoidae, only two species have been studied: the ultrastructure of spermatozoon and spermiogenesis of Gonapodasmius sp. (Justine & Mattei 1982) and of Didymozoon sp. (Justine & Mattei 1983, 1984).

The present study deals with the processes of spermatogenesis, spermiogenesis and the spermatozoon in a species of the family Didymozoidae, Didymocystis wedli Ariola, 1902, a parasite of Thunnus albacares recovered from the coast of the State of Rio de Janeiro, Brazil.

MATERIALS AND METHODS

RESULTS

DISCUSSION

ACKNOWLEDGEMENTS

To Antonia Lúcia dos Santos, Departamento de Helmintologia, Instituto Oswaldo Cruz (IOC-Fiocruz), for providing the fishes; to Dr Ortrud Monika Barth, Departamento de Virologia, IOC-Fiocruz, for the facilities offered and for the use of the electron microscope; and to Dr Simone Chinicz Cohen, Departamento de Helmintologia, IOC-Fiocruz, for her critical review of this manuscript.

REFERENCES

Figs. 1-2 | Fig. 3 | Fig. 4 | Figs. 5-6-7 | Figs. 8-9

⁺Corresponding author. Fax: +55-21-2260.4866. E-mail: mclara@ioc.fiocruz.br

⁺⁺Research fellow from Conselho Nacional de Desenvol-vimento Científico e Tecnológico, CNPq.

Received 14 November 2000

Accepted 25 April 2001