Mammalian Sperm Motility: Observation and Theory

Gaffney, Eamonn A.; Gadêlha, Hermes; Smith, D. J.; Blake, J. R.; Kirkman-Brown, Jackson

doi:10.1146/annurev-fluid-121108-145442

Cited by 341 publications

(398 citation statements)

References 144 publications

(128 reference statements)

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“…(13) for the active dipole, and the ratio λ of the hydrodynamic length to the total headtail length of a swimmers? If both these parameters are set to unity, the values of the activityσ are too low for all three species and predictions for live and dead cell suspensions are virtually indistinguishable, and these predictions are substantially different from the experimental data (dashed curves in Fig.…”

Section: Resultsmentioning

confidence: 99%

Motility induced changes in viscosity of suspensions of swimming microbes in extensional flows

McDonnell

Gopesh

et al. 2015

Soft Matter

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Suspensions of motile cells are model systems for understanding the unique mechanical properties of living materials which often consist of ensembles of self-propelled particles. We present here a quantitative comparison of theory against experiment for the rheology of such suspensions. The influence of motility on viscosities of cell suspensions is studied using a novel acousticallydriven microfluidic capillary-breakup extensional rheometer. Motility increases the extensional viscosity of suspensions of algal pullers, but decreases it in the case of bacterial or sperm pushers. A recent model [Saintillan, Phys. Rev. E, 2010, 81, 56307] for dilute active suspensions is extended to obtain predictions for higher concentrations, after independently obtaining parameters such as swimming speeds and diffusivities. We show that details of body and flagellar shape can significantly determine macroscale rheological behaviour.

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Section: Resultsmentioning

confidence: 99%

Motility induced changes in viscosity of suspensions of swimming microbes in extensional flows

McDonnell

Gopesh

et al. 2015

Soft Matter

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“…However, the tools for examining human sperm digital imaging microscopy are founded from an era where only the cell body, and not the flagellum, could be readily resolved [1,2]. Apart from some simulations of velocity magnitude [5] and surface attraction [6], there is relatively less detailed characterisation of the fluid dynamics associated with the human sperm flagellar beat.…”

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confidence: 99%

Coarse-Graining the Fluid Flow around a Human Sperm

et al. 2017

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“…It is believed that this attractive force has hydrodynamic origin although other possible mechanisms have been proposed [12][13][14]. Several models have been introduced to describe the swimming along surfaces (see Ref.…”

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confidence: 99%

Geometrical guidance and trapping transition of human sperm cells

et al. 2014

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The guidance of human sperm cells under confinement in quasi 2D microchambers is investigated using a purely physical method to control their distribution. Transport property measurements and simulations are performed with dilute sperm populations, for which effects of geometrical guidance and concentration are studied in detail. In particular, a trapping transition at convex angular wall features is identified and analyzed. We also show that highly efficient microratchets can be fabricated by using curved asymmetric obstacles to take advantage of the spermatozoa specific swimming strategy.PACS numbers: 87.17. Jj, 87.18.Hf, 87.17.Aa, 87.17.Rt Understanding sperm dynamics under confining microgeometries is a general problem and a major challenge both from the basic biophysics and the complex fluids points of view. It is also crucial for microfluidics and biomedical control applications. Our knowledge of the swimming cell motilities in unbounded media cannot be directly extrapolated to their behavior in complex environments such as those found in the oviduct or in the labon-a-chip microfluidic devices used to control and analyze small samples or for in-vitro reproduction procedures. In these cases, the characteristic length scales are of the same order as the cell size, i.e. a few micrometers. Under these circumstances, confined self-propelled microorganisms undergo substantial changes in their locomotion habits, adapting their dynamics to intricate porous media or to solid surfaces vicinity [1], reducing their speed close to boundaries [2] or adjusting their morphology and motility in very narrow channels [3].It has been shown that microswimmers with very different propulsion systems are similarly attracted to the walls and to swim parallel to the surface [2,[4][5][6][7][8][9][10][11]. It is believed that this attractive force has hydrodynamic origin although other possible mechanisms have been proposed [12][13][14]. Several models have been introduced to describe the swimming along surfaces (see Ref.[15] and references therein). Interestingly, the direct observation of the cell-wall attraction (see Fig. 1) have led to the design of ratchet devices that guide and sort self-propelled cells using asymmetric obstacles [16,17]. In particular, different microfluidic devices have been created to either increase sperm cell quality or enhance their concentration [18][19][20]. The creation of inhomogeneous distributions of swimmer populations via asymmetric obstacles has been shown to be particularly efficient for run-and-tumble bacteria [16,[21][22][23]. Alternative ways of achieving nonuniform distributions have also been obtained combining symmetric funnels and flux [24]. Nowadays, numerous theoretical treatments are available to account for the effects of asymmetric obstacles on active particles distributions [25][26][27][28]. Tumbles, rotational diffusion and collisions are efficient mechanisms for separating the cells from the surface, thus permitting bacteria to be reinserted into the bulk of the confining micro...

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Mammalian Sperm Motility: Observation and Theory

Cited by 341 publications

References 144 publications

Motility induced changes in viscosity of suspensions of swimming microbes in extensional flows

Motility induced changes in viscosity of suspensions of swimming microbes in extensional flows

Coarse-Graining the Fluid Flow around a Human Sperm

Geometrical guidance and trapping transition of human sperm cells

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