The fine-structure of the epimastigote forms of Trypanosoma lewisi in the rectum of the flea, Nosopsyllus fasciatus is described.
The parasites are attached to the rectal wall by penetration of the flagella between the highly folded wall of the rectum, by the wedging of the expanded flagella in these folds and irregularities of the wall and by a zonula adherens functional complex between the flagellar membrane and the cuticle of the rectum.
The parasites remain associated with each other by their flagella. The daughter axonemes produced during division are retained within the parent flagellar membrane; this delayed division of the flagella results in up to four axonemes being found within a single flagellar membrane. The parasites accumulate together in masses in the lumen of the rectum and their surfaces interdigitate resulting in the mass of parasites being retained together.
The financial assistance of the Agricultural Research Council is gratefully acknowledged. My sincere thanks are due also to my supervisor Dr Tate for his help, encouragement and enthusiasm through the course of this work.