Fig. 4

Morphology and staining of Clonorchis sinensis eggs and their surroundings in gallbladder bile (a, d, g, j), bile sediment (b, e, h, k), and gallbladder stones (c, f, i, l) under an optical microscope, with the arrow pointing to the eggs. (a, b, c) Eggs in three specimens examined under a microscope without staining. (d, e, f) Results of periodic acid-Schiff staining with red coloration. (g, h, i) Von Kossa staining: the brown to dark-brown colour indicates positivity for calcium salts. (j, k, l) Trypan blue staining: blue colour indicates non-viable or dead eggs