Diethylcarbamazine: In vitro Inhibitory Effect on Microfilarial Production by Dirofilaria immitis

Abstract

Hasstilesia ovis by Zdarska et al. (1983, Folia Parasitologica 30: 341-344). The acuminate, microtrichelike structures on Phyllobothrium sp. (Fig. 10) are morphologically different from all previously described microtriches and may be spines. The tangled, filamentous structures on the bothridial adhesive surface of P. monomegacantha (Fig. 6) are similar to microtriches reported for several other cestodes, e.g., Echinococcus granulosus by Thompson et al. (1982, International Journal for Parasitology 12: 579-583) and for Taenia hydatigena by Featherston (1975, International Journal for Parasitology 5: 615-619). Why these structures on the adhesive surface are of different sizes in the present species is not known. Perhaps the functional activity of each is different. The cylindrical microtrichelike structures which occur apically (Figs. 2a, 4) and on the outer bothridial surfaces (Fig. 3) of the scolex and on the neck (Figs. 7a, b) of P. monomegacantha are basically similar in appearance to those cylindrical structures which occur apically and on all bothridial surfaces of Phyllobothrium sp. Such cylindrical structures have been reported previously for numerous other cestode species, e.g., the protoscolex of Echinococcus multilocularis (Marchiondo and Andersen, 1983, Journal of Parasitology 69: 709-718); Taenia hydatigena (Featherston, 1975, loc. cit.); Diphyllobothrium dendriticum (Andersen, 1975b, International Journal for Parasitology 5: 293-300); Haplobothrium globuliforme (Thomas, 1983, Journal of Parasitology 69: 719-730) and for Proteocephalus ambloplitis (Jilek and Crites, 1980, Journal of Microscopy 118: 443-446). This cylindrical structure (microtriche ?) undoubtedly represents the more conventional pattern of microtriches among the adult cestodes. The frequent occurrence of microtrichial polymorphism in cestodes probably relates to functional variation for different regions of the tegument. See Thompson et al. (1980, Zeitschrift fur Parasitenkunde 64: 95-111) for review. Pits similar to those on the apex of P. monomegacantha (Figs. 2a, 4) have also been reported on the apical scolex of D. dendriticum and D. latum by Andersen (1975, International Journal for Parasitology 5: 487-493) and bothridial adhesive surfaces of Rhinebothrium ditesticulum by Whittaker and Carvajal G. (1980, Proceedings of the Helminthological Society of Washington 47: 256-259). Additional studies are necessary before any functions for the pits in the present species can be suggested.