Sperm Motility in Newtonian and Viscoelastic Fluids

We analyze the motion of mouse sperm swimming in fluid environments with varying concentrations of Ficoll and carboxymethyl cellulose (CMC). Using MATLAB, we extract consistent trajectories from videos, identifying "turbo tracks" which are sperm paths characterized by sustained directional movement of sufficient length. Notably, sperm swim faster in viscoelastic fluids than in purely viscous fluids at high viscosities and these speed differences appear to be largely related to shape changes that occur at these higher viscosities. To characterize the shape dynamics, we generate low-dimensional reconstructions of flagellar motion that still capture key flagellar dynamics.