Characterization of rheotaxis of bull sperm using microfluidics

Abstract

We study rheotaxis of bull sperm inside microchannels to characterize the effects of flow and wall shape on sperm swimming behavior. We found that a large percentage of sperm cells, 80 to 84%, exhibited positive rheotaxis (sperm cells swimming against the flow) within flow velocities of 33 to 134 μm s(-1). Sperm cells were also found to reverse their swimming direction when the liquid flow direction was reversed. Time taken by sperm cells to reverse their swimming direction was inversely proportional to the flow velocity. Sperm behavior was significantly affected by the sperm position with respect to the channel wall. Sperm cells close to the channel wall moved upstream faster than sperm cells moving along the channel centerline. Shear stress, which is an indicator of velocity distribution, was found to play an important role in regulating rheotactic behavior of sperm cells. Side pockets were added to some microchannels to mimic storage sites in mucosal folds and pockets in the fallopian tube of the female reproductive system and sperm interaction with these pockets was monitored. We found that sperm cells tend to follow channel walls and enter these pockets without any chemical binding, which further confirms the wall tracking behavior of mammalian sperm cells. Our results confirm that sperm rheotaxis is a strong mechanism for guiding sperm cells towards the oocyte along the female genital tract.

Designing 3-Dimensional In Vitro Oviduct Culture Systems to Study Mammalian Fertilization and Embryo Production

“…Research into microfluidics and reproductive events have increased in the past years, and relatively new papers on microfluidics and gamete development have been published 4,15,20,21,24,31,41,42,52,56,62,78,99,111,121,124. In most cases, these papers relate to sperm migration, and none have included OECs in the model.…”

Contribution of the CASA system, based on open source software, to the assessment of sperm characteristics: informetric and usage-based approaches

“…Computer-assisted sperm analysis supports numerous options for default values, making it possible to apply the analysis to virtually all fish species as well as to other taxa, as observed in mammals (Lemaitre et al, 2012;El-Sherry et al, 2014;Fisher et al, 2014;Jaiswal et al, 2014;Simpson et al, 2014), birds (Helfenstein et al, 2010a(Helfenstein et al, , 2010bLosdat et al, 2011;Simpson et al, 2014), and marine invertebrates (Fitzpatrick et al, 2010;Liu et al, 2011b;Sasson et al, 2012;Suquet et al, 2012;Simpson et al, 2014). As a result, fish sperm from 23 species from diverse environments has been studied to date.…”

Effect of pH on rheotaxis of bull sperm using microfluidics

“…Sperm rheotaxis was studied in microfluidic systems to understand how sperm interact with several flow conditions as flow speed, channel geometry and wall topography to confirm that rheotaxis is not a random effect. These previous studies showed that approximately 80% of motile sperm cells swim against the flow and reverse their swimming direction when flow direction is reversed (El‐Sherry et al., ). Moreover, when the flow speed increased, the sperm speed increased to counteract the flow.…”

“…Sperm rheotaxis, which is tendency of a sperm to orient and swim with or against the flow of surrounding fluid, is becoming important for understanding how mammalian sperm navigate through the female genitalia to reach the ovum (El‐Sherry, Elsayed, Abdelhafez, & Abdelgawad, ; Kantsler, Dunkel, Blayney, & Goldstein, ; Miki & Clapham, ; Tung, Ardon, Fiore, Suarez, & Wu, ). Coitus increases the secretion of oviduct dramatically and induces fluid flow that guides sperm cells swimming against the flow (i.e.…”

“…Recently, it was reported that positive rheotaxis has a physiological importance for the sperm travel through the genitalia to the site of fertilization in mice, human (Miki & Clapham, ; Suarez, ) and bull (El‐Sherry et al., ). Sperm rheotaxis was studied in microfluidic systems to understand how sperm interact with several flow conditions as flow speed, channel geometry and wall topography to confirm that rheotaxis is not a random effect.…”