title: Mechanical tuning of mammalian sperm behaviour by hyperactivation, rheology and substrate adhesion: a numerical exploration.
abstract: The great mammalian sperm race encounters numerous microenvironments to which sperm must adapt and a fundamental sperm response is the change in its waveform owing to both fluid rheology and capacitation, with the latter associated with a hyperactivated beat pattern. Hence, in this modelling study, we examine the effect of different flagellar waveforms for sperm behaviour near adhesive substrates, which are representative of epithelia in female tract sperm reservoirs and the zona pellucida (ZP), which surrounds the mammalian egg. On contact with an adhesive surface, virtual sperm rotate to become nearly tangential with the surface, as generally observed. Hyperactivation also induces many effects: sperm exert greater forces on the substrate and periodically tug way from adhesions under circumstances reflecting binding at sperm reservoirs, but with extensive fluid elasticity, as found in the cumulus surrounding the ZP, sperm instead continually push into the substrate. Furthermore, with weak adhesion, rheological media increase the duration hyperactivated sperm remain in the proximity of a substrate. More generally, such results predict that changes owing to both hyperactivation of the flagellar waveform and the rheology of the surrounding medium provide a means of tuning sperm behaviour near, or attached to, adhesive substrates.
authors.affiliation: The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8501, Japan ishimoto@kurims.kyoto-u.ac.jp.|Research Institute for Mathematical Sciences, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Kenta
authors.identifier: 0000-0003-1900-7643
authors.initials: K
authors.lastname: Ishimoto
authors.affiliation: Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK.
authors.forename: Eamonn A
authors.initials: EA
authors.lastname: Gaffney
mesh_terms: D060833:Cellular Microenvironment / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008954:Models, Biological; D013081:Sperm Motility / Q000502:physiology*; D013082:Sperm Tail / Q000502:physiology*; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D015044:Zona Pellucida / Q000502:physiology*
keywords: hyperactivation; mammalian fertilization; oviductal epithelium; sperm motility; sperm–zona binding