The tegument of adult S. mansoni.

Electron micrograph of a transverse section through the male tegument (T) and underlying musculature (M). The outer half is pitted (P, large arrowhead) extending the surface area, but notably lacks the microvillus-like microtriches of tapeworms, which acquire nutrients only across the tegument. The basal plasma membrane shows numerous infoldings (I, small arrowheads) typical of transporting epithelia. The cell bodies that contain the biosynthetic machinery lie below the muscle layer and are joined to the syncytium by narrow microtubule-lined cytoplasmic connections (CC, arrows). The inset shows the tegument surface at higher magnification revealing the two closely apposed lipid bilayers comprising an inner plasma membrane and an outer membranocalyx. The latter originates as the secreted contents of multilaminate vesicles (V, white arrows) that are produced by the Golgi apparatus in the cell bodies. Scale bars = 1 µm.