Figure 5. Immunolocalization of cathepsin F cysteine protease in adult Opisthorchis viverrini using thin sections of paraffin embedded worms probed with rabbit antiserum.

(A) Representative section spanning the gut, vitellaria, parenchyma and tegument, probed with pre-immunization serum (negative control). Sections of adults, probed with the rabbit anti-cathepsin F serum, the vicinity of the tegument and vitellaria (B), tegument and gut (C), and testis, seminal receptacle, parenchyma and eggs (D). Gut (g), vitelline glands (v), egg (e) and testis (T) all showed strong positive reactions whereas the sperm seminal receptacle (s) was negative. The tegument (t) was faintly positive but the tegumental cells were negative for the cathepsin F cysteine protease. Immunoperoxidase staining, original magnification, ×100.