Abstract: | Bicarbonate ions (HCO3?) in the medium are not absolutely essential for the fertilization of guinea pig eggs. However, fertilization takes place most efficiently in HCO3?-buffered medium. Capacitation, the acrosome reaction, and zona penetration by spermatozoa can occur in HCO3?-free media with synthetic organic buffers (i.e., MOPS, TES, HEPES, Tris, and TAPSO) but not as efficiently as in the HCO3?-buffered medium. It appears that HCO3? functions as more than just a pH-buffering molecule. |