Thin-layer chromatographic and histochemical analyses of neutral lipids in the intramolluscan stages of Leucochloridium variae (Digenea, Leucochloridiidae) and the snail host, Succinea ovalis.

Thin-layer chromatographic and histochemical analyses were used to analyze neutral lipids in the intramolluscan larval stages of Leucochloridium variae and in tissues of the snail host Succinea ovalis. Thin-layer chromatography showed that the major neutral lipids in uninfected snails were triacylglycerols and free sterols. The major neutral lipids in brood sacs minus their encysted metacercariae and in sporocysts were triacylglycerols and free sterols. Encysted metacercariae showed a significant free fatty acid fraction in addition to triacylglycerols and free sterols. Residual snail tissue (mainly head, foot, and visceral mass) from infected snails from which parasites were removed showed only a free sterol fraction. Histochemical staining of tissues with oil red O (ORO) showed the presence of neutral lipid droplets in the brood sac and sporocyst walls and mainly in the suckers, parenchyma, and excretory system of the encysted metacercariae. The residual snail tissue was ORO negative.