Ultrastructural observations on the epimastigote stages of Trypanosoma avium in Simulium rugglesi

Abstract

Epimastigotes of variable size, shape and density were observed adjacent to the cuticular lining of the hindgut and rectum of S. rugglesi that had fed 5 days previously on T. avium infected ducks. The parasites were aligned with their flagellar ends towards the cuticle with which they formed zonal hemidesmosomes. Cytoplasmic components of the epimastigotes included free ribosomes, a well-developed anteriorly and posteriorly directed, branched mitochondrial tube with associated kinetoplast, 2 types of lipid inclusions, homogeneous electron-dense vesicles, and lysosomelike bodies. Dividing epimastigotes were numerous and often possessed 2 kinetoplasts and flagella, and 4 basal bodies. Intranuclear spindle tubules were observed in some dividing nuclei, but were unfortunately poorly preserved.