Kinematic definition of ram sperm hyperactivation

Abstract

Although it is known that ram spermatozoa exhibit hyperactivated motility under capacitating conditions, quantitative analyses of the head and flagellar movement of washed ram spermatozoa have not been published. Motile spermatozoa were recovered from semen by swim-up into HSOF medium, and their movement in 30-µm-deep chambers was videorecorded. Spermatozoa of interest were identified during tape playback (hyperactivated spermatozoa were identified by visual assessment of flagellar movement) and sequential head and tail images were traced onto overhead projector film attached to the video monitor. The flagellar movement characteristics beat angle (FBA), beat envelope (FBE) and curvature ratio (FCR) were determined by first principles, and head centroid kinematics were determined using Cartesian methods. Hyperactivated spermatozoa had significantly higher FBA and FBE and significantly lower FCR values than non-hyperactivated spermatozoa (all P<0.0001). The centroid kinematic values were also found to be significantly different, and kinematic criteria for ram sperm hyperactivation were developed. These criteria were refined by consideration of 60-Hz CASA-derived trajectories, and ram sperm hyperactivation was defined by: VCL > 250.0 µm s ⁻¹ and VSL ≤ 100.0 m s ⁻¹ and LIN ≤ 30% and ALHmax ≥ 9.0 µm.