The migration of oncospheres of Taenia pisiformis, T. serialis and Echinococcus granulosus within the intermediate host

Heath D. D., 1971. The migration of oncospheres of Taenia pisiformis, T. serialis and Echinococcus granulosus within the intermediate host. International journal for Parasitology, 1: 145–152. The oncospheres of Taenia pisiformis and T. serialis hatched, became activated and penetrated the tips of the villi in the jejunal area of the rabbit small intestine. Similar results were obtained forE. granulosus, T. hydatigena and T. ovis in sheep. Most species of oncospheres appeared to progress down the villus beneath the columnar epithelium until a venule of diameter sufficient to allow passive transport to the liver was penetrated. The relatively large villus lacteal of ruminants, and the large diameter ofE. granulosus oncospheres, appeared to provide an opportunity for these organisms to penetrate the lacteal and translocate in the lymph. Parenteral inoculations of activated oncospheres indicated that T. pisiformis and E. granulosus oncospheres probably reach the liver in the portal vein. E. granulosus oncospheres infecting the lung may reach that organ in the lymph. T. serialis oncospheres were able to pass through both the liver and lungs in order to reach the muscles. A stimulus may exist in the liver causing cessation of movement and initiation of postoncospheral development for T. pisiformis and E. granulosus, but not T. serialis.