Fig. 5.

Microgrooves facilitate upstream swimming in sperm, but have no impact on T. foetus. (A) A montage of micrographs shows sperm (blue circles) swimming against the flow in a microgroove, whereas a T. foetus (red circles) does not enter the microgroove and is brought downstream. (B) Percentage of cells swept away by a 3 μL/min flow in three different situations: sperm swimming within microgrooves, sperm on a flat surface, and T. foetus on a flat surface. n = 50. Error bars show SEM. (C) Histogram of instantaneous x-velocity shows an upstream bias for sperm at a 3 μL/min flow and a downstream bias for T. foetus at 1 μL/min flow. Statistics were acquired from 50 tracks of sperm (2.81 s long) and 50 tracks of T. foetus (10.22 s long).