Figure 7. Trypanosome life cycle stages as solitary microswimmers in varying tsetse environments.
Infected tsetse flies were dissected in PBS and various regions, marked in the inset cartoon fly, were analysed by high speed microscopy (100 to 250 fps). Images are stills of the corresponding videos (Video 7), showing trypanosomes (white arrows) of various developmental stages. Scale bars: 10 µm. (A) Procyclic trypanosome swimming between blood cells in the posterior midgut lumen shortly after feeding. (B) A procyclic cell in tissue of the posterior midgut, confined by gut epithelium. (C) Procyclic to mesocyclic transition stages swimming along sheets of dissected PM in the anterior midgut. Trypanosomes experience different degrees of confinement and display characteristic straight trajectories and U-turns. (D) Various epimastigote cells inside the proventriculus, confined to a limited fluid-filled cavern. (E) Single metacyclic cells inside the thin salivary gland duct. The cells are motile, but mainly tumble around one position, as they await the tsetse fly´s next blood meal. Video 7 plays the original videos simultaneously with the annotated speeds.