A new objective method for scoring human sperm hyperactivation based on head axis angle deviation

The aims of the present study were, first to develop a new method for evalu ating sperm hyperactivation (HA) based on sperm head axis angle deviation, and second to apply this method in scoring selected sperm populations durin g capacitation. This was made possible by improving our original superimpos ed image analysis system (SIAS). The new option on the system enables us to determine the real angular deviation of the entire head in successive supe rimposed frames. The entire procedure for each spermatozoon requires 10-20 sec, according to the frame/rate utilized. A clear cut-off between the valu es of hyperactivated, transitional and non-hyperactivated spermatozoa was f ound at 11 and 21 frames/sec. However, at 6 frames/sec, a partial overlap b etween the three classes was found. We defined sperm activity as follows. A t 11 frames/sec, hyperactivated: angle sum greater than or equal to 405 deg rees; transitional: 200 degrees less than or equal to angle sum < 405 degre es. At 21 frames/sec, hyperactivated: angle sum greater than or equal to 76 0 degrees; transitional: 350 degrees less than or equal to angle sum < 760 degrees. The results, in agreement with previous research, show the peaks o f activity at 3 h, dropping to a minimum at 6 h. This phenomenon was signif icantly more evident in fertile compared with subfertile semen samples.