Effects of chamber depth on the motion pattern of human spermatozoa in semen or in capacitating medium

The computer-aided sperm analysis system (CASA) permits precise calculation of the trajectory characteristics of human spermatozoa. Comparison between different chamber depths (10, 20 and 100 μm) revealed variations in the results, which were more evident as the magnitude of the spermatozoon flagellar beat increased. In seminal spermatozoa, the reduced amplitude of movement, linked to the relatively short flagellum and high viscosity of seminal plasma, indicates that the 10 μm-deep chamber can be used for motion analysis without involving extensive modifications. On the other hand, analysis of quicker movement, such as in capacitated spermatozoa, revealed large variations; in particular the proportion of non-progressive hyperactivated spermatozoa was higher in the 20 μm than in the 10 μm chamber (17.9 ± 14% and 6.9 ± 4.5% respectively, P < 0.01). In fact the distribution of non-progressive and progressive hyperactivated spermatozoa is depth-dependent. It is therefore necessary to use a chamber of at least 20 μm in depth for sperm analysis in capacitated medium.