THE POTENTIAL SHORTCOMINGS OF MEASURING HYPERACTIVATED MOTILITY BY COMPUTER-AIDED SPERM ANALYSIS WHEN SPERM MOTION IS MULTIPHASIC

This paper was written from the standpoint that computer-aided sperm a nalysis (CASA) instruments, which capture a 'snapshot' of sperm trajec tories in order to generate their data, may provide a poor measure of hyperactivated motility in a sperm population where hyperactivation is multiphasic in nature, To illustrate this point, a series of theoreti cal sperm populations were constructed which varied subtly but signifi cantly in the nature of the hyperactivated behaviour expressed by sper matozoa, The parameters which were manipulated were: (i) the number of hyperactivated phases exhibited within a given period of time; (ii) t he duration of these phases; and (iii) proportion of spermatozoa withi n the population which exhibited hyperactivated phases, These populati ons were then subject to an analysis in which snapshots of sperm motio n were examined to determine the percentage of hyperactivated spermato zoa for that population, The results indicated that whilst this snapsh ot approach to quantifying hyperactivation could provide a figure for the percentage of hyperactivated spermatozoa within the sample window, this often inaccurately described the underlying behaviour of the pop ulation, Since there is very likely to be a significant amount of biol ogical information contained within the nature of multiphasic behaviou r, this paper has argued that this aspect of snapshot analysis is one which requires serious consideration by CASA manufacturers and medical researchers.