The histology of plerocercoid ofPenetrocephalus sp. reveal that the body surface consists of tegument, basement membrane, epidermal longitudinal musculature, parenchymatic longitudinal musculature, transverse and dorsoventral muscle fibres. Three types of glands could be recognized from the scolex of the plerocercoid. The musculature of the plerocercoid consists of glycogen, acid, sulfated, neutral and carboxylated mucopolysac-charides: basic proteins containing tyrosine, S-H and S-S groups, protein bound amino groups, sulfhydril groups, glycoprotein and lipid.
The frontal glands contain carbohydrates (1, 2 glycols, both acid and neutral mucopolysac-charides), basic protein (tyrosine, S-H group, protein bound amino group) and phospholipids. The structure, organization and histochemistry of the plerocercoid is discussed.