Scanning electron microscopy of newly excysted metacercariae of Paragonimus westermani-like, Nakhon Nayok, Thailand.

Scanning electron microscope (SEM) observation of surface structure was done on newly excysted metacercariae of Paragonimus westermani-like (Nakhon Nayok, Thailand). The surface of the body was covered with numerous single-pointed tegumentary spines, large dome-shaped papillae, small one with a pit, and small one with a smooth surface were situated around the suckers. There were 27 to 30 of the small dome-shaped papillae with a pit around the oral sucker and 10 to 13 of the small ones with a smooth surface around the ventral sucker. The present report is the new record of excysted metacercariae of P. westermani-like (Nakhon Nayok, Thailand) by SEM.

Eggshell morphology of the small eggs of human trematodes in Thailand.

Light and scanning electron micrographs of Opisthorchis viverrini, Haplorchis taichui, H. pumilio, A Phaneropsolus bonnei, and Prosthodendrium molenkampi eggs were studied. Under light microscopy. O. viverrini eggs had rough eggshells and prominent shoulders. H. taichui, H. pumilio were similar in shape and had smooth eggshells and prominent shoulders. H. pumilio eggs were bigger than H. taichui eggs. P. bonnei and P. molenkampi eggs had smooth eggshells and indistinct shoulders. P. bonnei eggs were thinner and bigger than P. molenkampi eggs. Some deformed eggs of O. viverrini and Haplorchis sp. were found and they had no embryos and indistinct opercula. Under scanning electron microscopy, O. viverrini eggs looked like musk-melon skin; they had prominent shoulders and long knobs. H. taichui eggs had curly, thread-like ridges and prominent shoulders and knobs. H. pumilio eggs had streched ridges, like Chinese bitter mormodica, and prominent shoulders. P. bonnei and P. molenkampi eggs had smooth eggshells and small shoulders and knobs.

Scanning electron microscopy of cuticular surface of the adults Paragonimus heterotremus in Phitsanulok, Thailand.

Scanning electron microscope observation of surface structure was made on adult Paragonimus heterotremus (Phitsanulok, Thailand) and the surface topography of the anterior end, suckers, body cuticle and papillae was described. The numerous thorn-like tegumentary spines were distributed all over the surface. The spines were well-developed and branched. The papillae were divided into two types: dome-shaped and ciliated. Two pairs of papillae were seen around the lip of the oral sucker, while those around the ventral sucker were not evident.