Ultrastructure of the digestive tract of Echinostoma revolutum cercaria.

The digestive tract of a fully formed free-swimming cercaria of Echinostoma revolutum (Froelich, 1802) Dietz, 1909 was studied by electron microscopy. The oral sucker and pharynx are covered by a tegument. The oesophagus and the caeca are not luminized. They are packed with giant epithelial cells with electron-dense granules of irregular shape, rough endoplasmic reticulum and its cisterns, and Golgi apparatus. The tegument of the oral sucker cavity contains numerous uniciliate receptors.