Quantitative analysis of surface micro-roughness alterations in human spermatozoa using atomic force microscopy

A new male contraceptive given the name RISUG (an acronym for Reversible Inhibition of Sperm Under Guidance) has been developed by our research group. RISUG is a bioactive polymer and is injected into the lumen of the vas deferens using a no-scalpel approach. The polyelectrolytic nature of this contraceptive induces a surface charge imbalance on sperm membrane system leading to its destabilization. Complete disintegration of the plasma membrane with subsequent rupture and dispersion of the acrosomal contents is observed on RISUG treatment. In the present study, micro-structural properties of human spermatozoa exposed to RISUG in vitro have been quantitatively analysed using atomic force microscopy. The parameters used to quantify these morphological changes include amplitude (peak-valley height difference, arithmetic roughness, root mean square roughness) and spatial roughness. Factor loadings (Varimax rotation) have been used to determine the parameters displaying maximum variation. Further, sperm cells have been classified in various principal-component planes using principal-component analysis. The periodic structural features of the atomic force microscopy images have also been obtained using power spectral analysis.