Antihelminthic Activity of the Drug, Oltipraz, on the Surface Ultrastructure of Schistosoma mansoni

When schistosomes and cestodes are exposed to unfavorable environmental conditions, one of the most important anatomical components that undergoes morphological and degenerative changes is the outer body wall (surface tegument). The primary function of the surface tegument is to mediate the intake of nutrients from the host environment. In addition, it facilitates the secretion of enzymes and regulates the ionic flow of water (Smyth, 1969; Lumsden and Specian, 1980; Threadgold, 1984; Jones et al., 1989; 1988, 1977a and 1977b). Concomitantly, the surface tegument provides a shield for the host and an immunological mechanism, thus allowing resistance to foreign substances (Lumsden et al., 1980). The structure of the surface tegument of schistosomes, particularly Schistosoma mansoni, has been studied utilizing ultrathin sections for transmission electron microscopy (TEM) (Senft et al., 1961; Silk et al., 1969; Smith et al., 1969; Lumsden and Specian, 1980) and by scanning electron microscopy (SEM) (Miller et al., 1972; Hockley, 1968; Johnson and Moriearty, 1969; Robson and Erasmus, 1970). These investigations have revealed that the surface tegument is a syncytium made up of a surface layer recognized as a cytoplasmic sheath or matrix, connected by cellular extensions to cell bodies (nuclei) buried in the parenchyma.