Increased velocity and induction of chemotactic response in mouse spermatozoa by follicular and oviductal fluids

The dynamic parameters of mouse sperm cells exposed to follicular and ovidu ctal fluids were assessed. Spermatozoa were tracked on a chemotactic Zigmon d chamber and recorded using a videomicroscopy system. The results were eva luated with computer-supported image analysis. Follicular fluid at a diluti on of 10(-4) markedly increased the proportion of spermatozoa with high vel ocity, and stimulated chemotactic behaviour. The highest velocities were ob served in sperm cells exposed to oviductal fluid, and a greater proportion of these cells had high velocity compared with those exposed. to follicular fluid. Chemotaxis was induced in spermatozoa exposed to oviductal fluid at dilutions of 10(-3) and 10(-5). These results suggest the presence of temp oral subpopulations of responsive spermatozoa, considering the distance tra velled towards both follicular and oviductal fluids and the proportion of s perm cells migrating towards the gradient in the highest distance ranges. T his is the first report on the effect of isolated follicular and oviductal fluids on dynamic parameters and chemotaxis of mouse spermatozoa. The findi ngs support previous work showing that the motility and directionality of m ouse sperm cells is increased by factors in the microenvironment of the egg . Although the significance of these factors in vivo is unknown, it is poss ible that there is a relay mechanism involving sequential activity of both oviductal and follicular fluids to direct the male gametes towards the egg.