No abstract

This work describes the first ultrastructural results on spermiogenesis and on the mature spermatozoon of Dicrocoelium hospes (Trematoda, Digenea) collected in Bos indicus from Senegal (Africa). Examination of this species was processed by TEM. Spermiogenesis follows the general pattern found in the digenean, but reveals a particularity consisting of the appearance of glycogen granules in the late spermatids within the testes. The mature spermatozoon possesses five distinct regions and presents all features found in Digenea gametes: two axonemes, mitochondria, nucleus and parallel cortical microtubules. However, several characters allow us to distinguish D. hospes from other digenetic trematodes within the Dicrocoeliidae family. In fact, we observed several structures that are absent in the other species of Dicrocoeliidae studied until now, such as: a cytoplasmic expansion, extramembranar ornamentation, spine-like bodies and two parallel mitochondria in the mature sperm. Moreover, additional particular characteristics were observed in this species in both extremities of the spermatozoon. This work produced new data on the ultrastructure of this trematode family which may be useful for phylogenetic purposes.

This paper describes the ultrastructure of spermiogenesis and the mature spermatozoon of two Dipylidiidae cestodes, Joyeuxiella echinorhynchoides and J. pasqualei. In both species, spermiogenesis follows the type III described by Bâ and Marchand for the cyclophyllideans. Nevertheless, it is interesting to note the presence of striated roots associated with the centrioles. The spermatozoon presents the same ultrastructural features in J. echinorhynchoides and J. pasqualei. The apical cone in the anterior extremity of the sperm is more than 2.0 microm long in both J. echinorhynchoides and J. pasqualei. Both species present a single crest-like body, 150 nm thick in J. echinorhynchoides and 75 nm thick in J. pasqualei. The cortical microtubules are spiralled at an angle of 40-45 degrees to the spermatozoon axis in both Joyeuxiella species. A periaxonemal sheath and glycogen granules are also described in the mature sperm. We also describe, for the first time, the disposition of glycogen granules in two opposed and spiralled cords in cestodes and the formation of the periaxonemal sheath in the final stage of spermiogenesis.