Scanning electron microscope observations on miracidium, cercaria, and cercarial papillar patterns of Schistosoma japonicum.

The surfaces of Schistosoma japonicum miracidia and cercariae were examined with the scanning electron microscope, and argentophilic papillae of S. japonicum cercariae, presumed to be sensory, with both the scanning electron microscope and the light microscope. Miracidia are covered with cilia, and the apical papilla is covered with cytoplasmic folds that form an anastomosing network. There is an excretory pore on the posterior one-third of the body. The tegument of S. japonicum cercariae is covered with spines that point in a posterior direction. The tail has a more irregular surface than the body, with fewer spines. The openings of the penetration gland ducts on a disclike area with netlike ridges at the anterior tip of the head organ are linearly arranged in 2 lateral crescents each containing 7 separate apertures. The basic number of the body papillae of S. japonicum (excluding those at the anterior end) is 56: 18 ventral, 4 acetabular, 18 dorsal, and 16 lateral (8 on each side). The number of papillae at the anterior tip is 14 (7 on each side). There are 9 papillae on the ventral side of the tail, and 10 on the dorsal and lateral sides.