Fine Structure of the Integument of the Cryptocotyle Lingua Redia

Abstract

Recent electron microscope studies of trematode rediae have revealed microvilli projecting from the integument, presumably to facilitate exchange of materials between the parasite and the snail host. This report on the redia of Cryptocotyle lingua extends these observations and provides an additional basis for future biochemical studies of host-trematode relations. The rediae were removed from crushed snails (Littorina littorea), washed in filtered sea water, fixed in 5% glutaraldehyde-paraformaldehyde solution in sea water, postosmicated, and embedded in Epon in the usual manner.Light microscopy shows that the apical surface of the redial body wall has numerous undulations or corrugations of varying dimensions and shapes (Fig. 1, arrow). As seen in the electron microscope, many cytoplasmic projections or microvilli stem perpendicularly from these crests and valleys (Figs. 2,3). In tangential sections of the redial surface (Fig. 4), the microvilli appear as thin, flat structures or spatulae, rather than as cylindrical, digitiform projections. The expanded surface of some microvilli is also suggested in sagittal- sectioned rediae (Fig. 2).