Echinostoma caproni: differential tegumental responses to growth in compatible and less compatible hosts.

The topography of the tegument of Echinostoma caproni adults collected from high (mice) and low (rats) compatible hosts was compared by SEM. In the oral (OS) and the ventral sucker (VS) areas, a worm age-host species interaction was found with regard to the density of spines. There was a decrease in the density of spines in the adults collected from mice, whereas an increase occurred in the OS area in worms from rats over time. The tegumentary spines in adults from mice became larger and blunter. Some spines from the VS area in adults from mice at 4 wpi were multipointed. The spines of adults from rats were sharper, not covered by the tegument and no multipointed spines were observed. We detected a greater level of actin gene expression in the adults collected from rats. These facts suggest that the low compatible host induces an increased turnover of tegumentary spines.