Early development of Taenia crassiceps in the intermediate host, with a note on primitive cell types

Abstract

The observations on the early development of T. crassiceps indicate that in the intermediate host the 2-day-old embryo is a solid structure with hooks. The beginning of the disappearance of hooks and the appearance of an eccentric cavity, the lacuna, takes place somewhere between 2-4 days of development. Even if the embryonic hooks are not lost during the first 4 days of development, they are no more functional. An obvious host tissue reaction was noticed in the early stages of development of T. crassiceps. In a living embryo (= metacestode) the flickering movement of flame cells was first noticed after 12 days of development. Most of the cells in the developing metacestodes had vesicular nuclei and little cytopIasm. Besides these developing flame cells, nerve cells and cells similar to the fibroblasts of other animals were also noticed. A comparison of the early development of T. crassiceps in the subcutaneous tissues and in the peritoneal cavity of the intermediate host clearly shows that the metacestodes grow faster in the subcutaneous tissues than in the peritoneal cavity.