Doing more with less: The flagellar end piece enhances the propulsive effectiveness of human spermatozoa

Abstract

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Computer-assisted beat-pattern analysis and the flagellar waveforms of bovine spermatozoa

“…With such extensive flagellar detail captured, we consider the previously unavailable metric of maximal distal curvature (MDC), suggested by Neal et al [ 16 ] to be correlated with swimming efficiency. We compute the MDC of each of the swimmers throughout their beat, as described in the Methods and material, which are shown as histograms in figure 5 c stratified by sample.…”

“…Further, the expansion into near-complete planar flagellar waveform capture offers the prospect of novel directions for the exploration of male gamete motility, and flagellated or ciliated organisms more generally. The significance of high-fidelity analysis of flagella is further highlighted by the recent work of Neal et al [ 16 ], with the overall efficiency of a spermatozoon suggested to be linked to distal curvature. Measurement of such curvatures requires the capture of large proportions of the flagellum, greater than previously available en masse with readily accessible microscopy as demonstrated here to be achievable on significant sample sizes, though with further developments in imaging and subsequent image processing required to capture complete details of the distal flagellum.…”

“…With the data in this study capturing all but the most distal 10% of the observed flagellum, with processed data screened by this requirement, this measure is therefore computed over 81% and 90% of the true flagellum length and thus may not represent the true curvature of the most distal tip of the beating flagellum. However, the MDC as defined here captures details of the distal flagellar region previously unavailable on this scale, with the distal portion of the flagellum recently suggested to be correlated with overall swimming efficiency [ 16 ].…”

Regularised non-uniform segments and efficient no-slip elastohydrodynamics

“…With force density a fundamental component of such elastohydrodynamic frameworks, these apparent errors may contribute non-negligibly to the simulated dynamics and applications, particularly given the reported significance of distal activity in recent model spermatozoa (Neal et al. 2020). Thus, the absence of comparable oscillations in the RNS solutions represents a significant advantage over these existing methodologies.…”

“…(2019) to include improved non-local hydrodynamics, applied to the model biological problem of flagellar efficiency (Neal et al. 2020), and extended to motion in three dimensions (Walker, Ishimoto & Gaffney 2020 b ).…”