Sperm Travel in 'Channel Corners,' Not in Channel Center

(HealthDay News) – Sperm cells travel in the intersection of channel walls, not in central channels, and experience frequent collisions.

Petr Denissenko, PhD, from the University of Warwick in Coventry, UK, and colleagues examined the behavior of migrating sperm in assorted micro-channel geometries to elucidate the individual and group behaviors that may occur in the female tract environment.

The researchers found that cells rarely swim in the central part of the channel cross-section, but rather travel in "channel corners," along the intersection of the channel walls. Cells leave the corner when a channel turns sharply and continue until hitting the opposite wall, with a distribution of departure angles modulated by fluid viscosity. In smooth channel bends, when the radius of the curvature is less than a threshold value close to 150µm, cells depart from the inner wall. Motile cells can be directed preferentially by specific wall shapes. The domain occupied by the cells swimming along the corners is essentially one-dimensional, which results in frequent collisions.

"Sperm cell migration in a micro-channel crucially depends on the channel geometry. Cells swim along boundaries and, if the two flat boundaries intersect, cells follow the corner. This has cardinal consequences for modeling of the cell behavior," the authors write.

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