Surface ultrastructure of newly excysted metacercariae of Paragonimus heterotremus.

The newly excysted metacercariae of P. heterotremus were examined by scanning electron microscopy (SEM). Large dome-shaped papillae, small ones with a pit, and small ones with a smooth surface were observed around the suckers. The number of the small dome-shaped papillae with a pit was about 30 around the oral sucker and that of the small ones with a smooth surface varied from 9 to 13 around the ventral sucker. The present report is the first record of excysted metacercariae of P. heterotremus examined by SEM.