MOUSE SPERMATOZOA MODIFY THEIR MOTILITY PARAMETERS AND CHEMOTACTIC RESPONSE TO FACTORS FROM THE OOCYTE MICROENVIRONMENT

The aim of this work was to evaluate the period of time required for t he induction of changes in motility of mouse spermatozoa in response t o factors from the microenvironment of oocytes. To determine the effec ts of the latency time, the period of preincubation before contact wit h the oocyte product(s), sperm samples were incubated for 15 or 90 min and then exposed to either Dulbecco's Modified Eagle's Medium (DMEM) or to a crude extract of superovulated oocytes (CE). The assays were p erformed in a Zigmond chamber by filling one compartment with either D MEM or CE, and the other compartment with the sperm suspension. A vide omicroscopy system was used for tracking the spermatozoa. Sperm motili ty analysis was assessed using a semiautomatic objective method, and t he following parameters were determined. (1) dynamic parameters: curvi linear velocity, linear velocity and linearity; (2) progressive motili ty: percentage of spermatozoa showing either circular or linear patter ns of movement; and (3) directional motility: percentage of spermatozo a that moved towards either the DMEM or the CE. The results of this wo rk showed that when the spermatozoa contacted soluble factors in CE af ter only 15 min of previous incubation, there was a significant increa se in their dynamic parameters, change ill their progressive motility, and induction of directional movement of the spermatozoa towards the CE components, while a longer period of preincubation did not signific antly modify these effects. On the other hand, in the presence of cult ure medium (with or without addition of bovine serum albumin), the spe rmatozoa needed a more extended period of incubation to significantly increase their dynamic parameters and to modify their progressive moti lity, while maintaining a random direction of movement.