Selected human sperm population at the collection well of the microfluidic device. Sperm progression was recorded under 100X magnification on an inverted microscope (CK40; Olympus, Center Valley, USA). This video (http://movie-usa.glencoesoftware.com/video/10.1530/REP-20-0364/video-5) is available from the online version of the article at https://doi.org/10.1530/REP-20-0364.