SCANNING ELECTRON MICROSCOPIC OBSERVATION ON THE DEVELOPMENT OF CLONORCHIS SINENSIS IN RATS

Clonorchis sinensis on days 1、3、5、7、9、13、16、20、23 postinfection were obtained from the liver of rats artificialy infected with 30 metacercariae of Clonorchis sinensis. Ten to fifteen worms were scanned on each of the days listed.The results are as follows: with development the tegumental transverse ridges increased gradually in height and became knoblike protuberances which were potato-like in appearance; some finger-shaped and much longer branch-shaped projections extended from the knob surface; the tegumental spines decreased gradually; At 20—23 days postinfection, the spines were not yet compeletly disappeared. At 1—23 days postinfection, 8—12 sensory papillae were observed on the lip of the oral sucker. At 1—5 days postinfection, the type and distribution of papillae on the ventral sucker were almost identical with that of metacercaria, but at 16, days postinfection the papillae on the ventral sucker increased markedly.At 9 days postinfection, the papillae around the oral and ventral suckers increased. At 1—23 days postinfection, the papillae were scattered randomly over the tegumental strface, sometimes they were parallel to the sides of the body. With development, the size of the excretory pore increased, and it sank in at 16 days postinfection, around which 6—14 papillae with long or short cilia were seen.Investigations described above suggest that the changes of tegumental spines and the distribution of tegumental sensory papillae are related to the physiological adaptation of the fiuke in the course of development in rats.