Chemotaxis of Capacitated Rabbit Spermatozoa to Follicular Fluid Revealed by a Novel Directionality-Based Assay1

FABRO, GEORGINA; ROVASIO, ROBERTO A; CIVALERO, S; FRENKEL, ANAT; CAPLAN, ROY; EISENBACH, MICHAEL; GIOJALAS, LAURA

BIOLOGY OF REPRODUCTION

SOC STUDY REPRODUCTION

Lugar: Madison, Wisconsin, USA; Año: 2002 vol. 67 p. 1565 - 1571

0006-3363

Precontact communication between gametes is establishedby chemotaxis. Sperm chemotaxis toward factor(s) in follicularfluid (FF) has been demonstrated in humans and mice. In humans,the chemotactic responsiveness is restricted to capacitatedspermatozoa. Here, we investigated whether sperm chemotaxisto factor(s) present in FF also occurs in rabbits and, if so,whether only capacitated spermatozoa are chemotactically responsive.Chemotaxis assays were performed by videomicroscopyin a Zigmond chamber. We measured chemotactic responsivenessas a function of FF dilution by means of a novel directionality-based method that considers the ratio between the distancestraveled by the spermatozoa both parallel to thechemoattractant gradient and perpendicular to it. A peak ofmaximal response was observed at 1024 dilution of FF, resultingin a typical chemotactic concentration-dependent curve inwhich 23% of the spermatozoa were chemotactically responsive.In contrast, the percentage of cells exhibiting FF-dependentenhanced speed of swimming increased with the FF concentration,whereas the percentage of cells maintaining linear motilitydecreased with the FF concentration. The percentages of chemotacticallyresponsive cells were very similar to those of capacitatedspermatozoa. Depletion of the latter by stimulation ofthe acrosome reaction resulted in a total loss of the chemotacticresponse, whereas the reappearance of capacitated cells resultedin a recovery of chemotactic responsiveness. We concludethat rabbit spermatozoa, like human spermatozoa, are chemotacticallyresponsive to FF factor(s) and acquire this responsivenessas part of the capacitation process.