Comparison of surface structures by SEM between 42-day-old adult worms in the NC group vs. the S1 siRNA group (10 injections via the tail vein at 4–42 dpi). Compared with the control siRNA group, SjFrzb2-S1 siRNA induced wall disarrangement of females with notably larger wall protrusions (A, B); increased bubbles, and flower-like papillae with abnormal structures between the oral and ventral suckers of female worms (C, D). The surface appearance was similar, with disordering of the network structure of the gynaecophoral canal posterior portion (E, F). The bubbles were obviously larger on the distal-end body wall of males (G, H). flp: flower-like papillae, ns: network structure, p: protrusion, b: bubbles.