Scanning electron microscopy of adult Dicrocoelium dendriticum.

Scanning electron microscopy (SEM) has been used to study the tegument and related structures of adult Dicrocoelium dendriticum. Its body shape, suckers, common genital pore, Laurer's canal pore, excretory pore, and cirrus are described as seen under SEM. The tegument is devoid of spines and presents an interlacing, ridged network which covers the entire body. The pattern of ridges on the body surface is not homogeneous; details of the pattern in each region are described. SEM of the body surface reveals the high density of tegumental vesicles on ridge walls and valley floors. The tegument also bears small finger-like projections in certain areas. The authors suppose that the vesicles and finger-like projections of the tegument may well be the same structure in different functional stages. Some considerations on the significance of the tegumental differences in each body region are given. Four types of tegumental papillae occur on the suckers and body surface of D. dendriticum: button, rosette, plate, and domed. The dimensions, shapes, position, and arrangement of the papillae are described.