Manual of basic techniques for a health laboratory - libdoc.who.int

4. Parasitology 139Fig. 4.66 Heterophyes heterophyeseggsFig. 4.67 Hymenolepis diminuta eggContent: a mass of cells, sometimes with large shiny granules (unfertilized) or aciliated embryo.Colour: yellow to dark brown.Hymenolepis diminuta (Fig. 4.67)Rare species (found in children’s stools).Size: 70–90mm (much larger than H. nana).Shape: round.Shell: external shell thin with transverse lines; internal shell very thick withoutfilaments.Content: a rounded embryo containing six hooklets arranged in fan shape.Colour: transparent or pale yellow.Hymenolepis nana (Fig. 4.68)Size: 40–60mm.Shape: oval, almost round.Shell: double; external membrane thin and internal membrane often thicker at thepoles, with filaments coming away from both poles (reduce the intensity of themicroscope light source to see them), mixed with granules occupying the spacebetween the two membranes.Content: rounded mass (embryo) with six shiny hooklets arranged in fan shape andoften some well-defined granules in the centre.Colour: very pale grey.Important: Record whether there are many or few eggs present.Metagonimus yokogawai (Fig. 4.69)Similar to the eggs of Clonorchis sinensis and Heterophyes heterophyes (see Figs. 4.49and 4.66).Size: 25–30mm.Shape: oval, with no marked shouldering.Shell: thicker than C. sinensis and H. heterophyes.Operculum: more rounded than in H. heterophyes; overlapping less than in C. sinensis.Boss: tiny or invisible, at the narrower end of the egg.Content: a ciliated embryo.Fig. 4.68 Hymenolepis nanaeggFig. 4.69 Metagonimusyokogawai egg