Mouse spermatozoa modify their motility parameters and chemotactic response to factors from the oocyte microenvironment

Abstract

The aim of this work was to evaluate the period of time required for the induction of changes in motility of mouse spermatozoa in response to factors from the microenvironment of oocytes. To determine the effects of the latency time, the period of preincubation before contact with 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 performed in a Zigmond chamber by filling one compartment with either DMEM or CE, and the other compartment with the sperm suspension. A videomicroscopy system was used for tracking the spermatozoa. Sperm motility analysis was assessed using a semiautomatic objective method, and the following parameters were determined: (1) dynamic parameters: curvilinear velocity, linear velocity and linearity; (2) progressive motility: percentage of spermatozoa showing either circular or linear patterns of movement; and (3) directional motility: percentage of spermatozoa that moved towards either the DMEM or the CE. The results of this work showed that when the spermatozoa contacted soluble factors in CE after only 15 min of previous incubation, there was a significant increase in their dynamic parameters, change in their progressive motility, and induction of directional movement of the spermatozoa towards the CE components, while a longer period of preincubation did not significantly modify these effects. On the other hand, in the presence of culture medium (with or without addition of bovine serum albumin), the spermatozoa needed a more extended period of incubation to significantly increase their dynamic parameters and to modify their progressive motility, while maintaining a random direction of movement.