VARIABLE KINEMATICS OF CAPACITATING HUMAN SPERMATOZOA

Human spermatozoa were prepared by swim-up from semen into in-vitro fe rtilization (IVF) culture medium, and their movement recorded by video micrography using NTSC video to give 60 images/s on freeze-frame playb ack. Trajectories in which spermatozoa appeared to switch from one typ e of motility pattern to another (from non-hyperactivated to transitio nal or star-spin hyperactivated), were reconstructed manually and the movement characteristics determined for short consecutive sequences al ong each track, The spermatozoa were able to switch between all of the se motility patterns, apparently at random, These observations illustr ated that hyperactivated motility is a reversible state in human sperm atozoa, with phase changes from hyperactivated to non-hyperactivated m otility patterns along trajectories. It was not necessary for spermato zoa to pass through the transitional hyperactivated motility phase whe n switching from non-hyperactivated to star-spin hyperactivated motili ty or vice versa.