Quantitative observations of flagellar motility of capacitating human spermatozoa.

Abstract

For technical reasons sperm head movement is assessed in kinematic analysis, while flagellar movement is the determining factor of head movement, not vice versa. It follows then that the development of new kinematic values to describe the movement of capacitating human spermatozoa should include the analysis of their flagellar movement. The aim of this study was to establish quantitative differences between flagellar movement patterns of hyperactivated and non-hyperactivated spermatozoa which could then be used in the evaluation of new centroid-based kinematic values. Spermatozoa were prepared by swim-up from semen into culture medium supplemented with 30 mg/ml human serum albumin. Sperm movement was recorded in 50 microm-deep chambers using a 200 Hz video system. Sperm movement was classified based on flagellar movement, with 24 non-hyperactivated and 26 hyperactivated spermatozoa included in the study. Flagellar analysis was performed using both a semi-automated analysis system (SIAM FLAG; 30 images at 200 Hz) and manual methods (100 Hz). Hyperactivated spermatozoa had significantly larger flagellar beat angles (> or = 87 degrees) and significantly lower flagellar beat frequencies (< or = 29.4 Hz) than non-hyperactivated human spermatozoa. In addition, the flagellar wave amplitude was significantly greater and the bend diameter significantly smaller for hyperactivated spermatozoa in the proximal region of the flagellum (up to 20 microm from the head-midpiece junction). The velocity of the hyperactivated wave was low in this region, although it was significantly slower than the non-hyperactivated wave in all regions of the sperm tail.