Tegumental ultrastructure of the juvenile and adult Himasthla alincia (Digenea: Echinostomatidae)

초록

The tegumental ultrastructure of juvenile and adult Himasthla alincia (Digenea:Echinostomatidae) was observed by scanning electron microscopy. One-, 5- (juveniles) and 20-day-oldworms (adults) were harvested from chicks experimentally fed metacercariae from a bivalve, Mactraveneriformis. The juvenile worms were elongated and curved ventrally. The head crown bore 31 collar spines,arranged in a single row. The lip of the oral sucker had 12 paired, and 3 single type I sensory papillae, andthe ventral sucker had about 25 type II sensory papillae. The anterolateral surface between the two suckerswas densely packed with tegumental spines with 4-7 pointed tips. The adult worms were more elongated andfilamentous, and had severe transverse folds over the whole body surface. On the head crown and twosuckers, type I and II sensory papillae were more densely distributed than in the juvenile worms. Retractilebrush-like spines, with 8-10 digits, were seen on the anterolateral surface, whereas claw-shaped spines, with2-5 digits, were sparsely distributed posteriorly to the ventral sucker. The cirrus characteristically protrudedout, and was armed with small spines distally. The surface ultrastructure of H. alinciawas shown to be uniqueamong echinostomes, especially in the digitation of its tegumental spines, the distribution of sensory papillaeand by severe folds of the tegument.

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