Free movement of Tritrichomonas foetus in a liquid medium: a video-microscopy study

The present paper describes in detail the complex movement of the protozoon Tritrichomonas foetus. By the use of analogue and digital video techniques, we were able to analyze frame by frame the beatings of the anterior flagella and discuss their role in the movement of the cell. We also measured the productive displacement of the cell during one flagellar beating cycle. The obtained data were digitally improved and compared to analogue quantifications. It is shown that during 1 s of recorded movement, T. foetus performs 4 complete anterior flagella beating cycles (with active-like and recovery-like beatings). In each cycle the cell swims +/- 6.5 microns forwards, after the recovery of +/- 1.5 microns of receded movement. These observations led us to conclude that the estimated average speed of T. foetus is 25 microns/s, and that all flagella participate in the cell movement. The recurrent flagellum continuously contribute to the forward movement of the protozoon. The cell also performs rotational movements. The obtained results led us to suggest a model for the movement of T.foetus.