Morphology of Opisthorchis viverrini s.l. cercariae. (A) Photomicrograph of unstained cercaria fixed in 10% NBF, (B) drawing image, (C) measured morphological characters. Abbreviations in (A) and (B): os = oral sucker, pa = pharynx, es = eye spot, pg = penetration gland, ivs = inconspicuous ventral sucker, eb = excretory bladder, sh = sensory hair, tst = transversely striated tegument, ta = tail, df = dorso-ventral finfold. The definition of abbreviations in (C) was showed in the first column of Table 4. Total length = length of purple dashed arrow + TL + length of orange arrow (at the position following the end of the tail).