Rapid sperm capture: High-throughput flagellar waveform analysis

Abstract

Flagella are critical across all eukaryotic life, and the human sperm flagellum is crucial to natural fertility. Existing automated sperm diagnostics (CASA) rely on tracking the sperm head and extrapolating measures. We describe fully-automated tracking and analysis of flagellar movement for large cell numbers. The analysis is demonstrated on freely-motile cells in low and high viscosity fluids, and validated on published data of tethered cells undergoing pharmacological hyperactivation. Direct analysis of the flagellar beat reveals that the CASA measure beat cross frequency, does not measure beat frequency. A new measurement, track centroid speed, is validated as an accurate differentiator of progressive motility. Coupled with fluid mechanics codes, waveform data enables extraction of experimentally intractable quantities such as energy dissipation, disturbance of the surrounding medium and viscous stresses. We provide a powerful and accessible research tool, enabling connection of the cells mechanical activity to its motility and effect on its environment.