Surface electrical characteristics of human spermatozoa as correlates of their acrosomal status

The present study attempts to characterize the acrosomal status of human spermatozoa with emphasis on their surface electric charge characteristics. Acrosome reaction is induced by a calcium ionophore A23187. Microelectrophoretic mobilities of the cells are observed under a potential gradient of 2V cm^-1 and zeta potentials determined that decrease from -18.49±0.41 mV for unreacted spermatozoa to -13.66±0.028 mV for acrosome reacted spermatozoa. The tails of unreacted spermatozoa lead their heads during migration towards the anode. This directionality is lost in reacted spermatozoa. Scanning electron micrographs following staining with colloidal iron hydroxide particles confirm the existence of charge gradient in unreacted supermatozoa. The charge density is seen to increase from acrosomal region to tail in unreacted cells. Though reacted spermatozoa do not show this charge gradient, yet a bright band is observed in the equatorial segment suggesting accumulation of anionic domains in this plane