Effect of Follicular or Oviductal Fluids on Movement Characteristics of Bovine Sperm during Capacitation In Vitro

Abstract

ABSTRACT: Mammalian sperm exhibit characteristic motility changes associated with capacitation. Movement characteristics of bovine sperm incubated in noncapacitating (control, medium alone), capacitating (oviduct fluid, nonluteal, and luteal), or capacitating, acrosome reaction inducing (follicular fluid) conditions were investigated using a computer‐assisted automated semen analysis system. Sperm were incubated up to 4 hours in a modified Tyrode's medium (control), 20 and 60% nonluteal (NL) or luteal (L) oviduct fluid (ODF), or 20 and 60% follicular fluid (FF). Relative to sperm incubated in control medium, motility of sperm treated with ODF or FF had increased linearity and vigorous motility. Sperm incubated in 60% ODF or FF showed a small decrease in mean trajectory/path straightness and velocity over time compared to 20% fluid treatments and control. Frequency distribution graphs were symmetric for 20% NL‐ and L‐ODF treated sperm. However, 20% FF and 60% ODF and FF treatments had distributions skewed to the left, indicating smaller values for lateral head displacement (ALH) and curvilinear velocity (VOL). Me dian values for ALH and VCL were determined for control‐treated sperm, and subtracted from individual sperm values for all treatments to estimate deviation from control, designated ALHc and VCLc. Three‐dimensional plots of ALHc, VCLc and corresponding frequency indicated shifts in peak patterns for fluid‐treated sperm compared to control sperm. Incubation in 20% ODF and FF resulted in peak shift for ALH and VCL values; yet, little change in peak position was observed in sperm incubated in 60% ODF and FF. Although mean values decreased for ALH and VCL during the 4‐hour incubation, three‐dimensional plots suggested an increase in the frequency of individual sperm with these parameters. This study provides additional information on bovine sperm motion during in vitro capacitation and indicates that the presence of ODF and FF influences sperm motion characteristics.