Research Note Excystation and Distribution of Metacercariae of Echinostoma caproni in ICR Mice

摘要

In vivo excystation and distribution of newly excysted metacercariae of Echinostoma caproni Richard, 1964, were studied in 16 ICR mice, each fed 400 metacercarial cysts and necropsied at various intervals from 1 to 24 hr postinfection (p.i.)- Excysted metacercariae were recovered from the stomach and intestine (duodenum and jejunum) at 1 hr p.i. In vivo excystation in this echinostome occurred in the stomach and the anterior part of the small intestine. Encysted metacercariae were recovered from the stomach, small intestine, and cecum-large intestine at 1 and 2 hr p.i. Recovery of encysted metacercariae was rare at 3 hr and nil at 4 and 24 hr. At 3, 4, and 24 hr, the encysted metacercariae had either excysted or were voided, Excysted metacercariae were widely scattered throughout the small intestine at all times, with about 75(percent) located in segments 1, 2, and 3 (duodenal-jejunum zone) of the small intestine at 3, 4, and 24 hr p.i.