An SEM study of the haptoral sclerites of the genus Gyrodactylus Nordmann, 1832 (Monogenea) following extraction by digestion and sonication techniques

Techniques for the preparation of haptoral sclerites of Gyrodactylus species for scanning electron microscopy are described. Enzymatic digestion using pepsin allows fresh, frozen and alcohol-fixed material to be examined, but some sclerites, such as the dorsal and ventral bars, are lost. Sonication of fresh and frozen material retained these accessory bars, including the ventral bar membrane, the guard or sickle filament loop on the marginal hooks and even on some occasions ligaments associated with the sclerites. The sclerites of Gyrodactylus spp. from Gasterosteus aculeatus (L.) (three-spined stickleback), Oncorhynchus mykiss (Walbaum) (rainbow trout) and Salvelinus alpinus (L.) (charr) are described from SEM observations following the use of these preparation techniques, and the articulation between the hamuli and bars is commented upon.