The histology, ultrastructure, and histochemistry of the ventral surfaces of Catatropis verrucosa (Froelich, 1789) Odhner, 1905 and Paramonostomum alveatum (Mehlis in Creplin, 1846) Lühe, 1909 (Digenea: Notocotylidae)

Abstract

Catatropis verrucosa (Froelich 1789) Odhner 1905 and Paramonostomum alveatum (Mehlis in Creplin, 1846) Lühe 1909 were examined using light and scanning and transmission electron microscopy. The ventral ridge, papillae, and body margins of C. verrucosa contained numerous pyriform cells packed with mitochondria. Paramonostomum alveatum has no ventral projections and no pyriform cells full of mitochondria were seen within the worms. Both species contained numerous large electron-dense inclusions in various tissues throughout the body. Histochemistry indicated that these inclusions were lipid or lipoprotein, but their function is unknown. Protein, including haemoglobin, and lipid were identified within the pyriform cells of C. alveatum. Paramonostomum is the only genus within the Notocotylinae examined to date that has no ventral projections nor any internal aggregation of cells packed with mitochondria.