Comparative study of the effect of human cervical mucus and a cervical mucus substitute, Healonid, on capacitation and the acrosome reaction of human spermatozoa in vitro

The present study was designed to investigate the effect of human cervical mucus on capacitation and the acrosome reaction of human spermatozoa and compare its effect to that of a cervical mucus substitute, sodium hyaluronate (Healonid). Spermatozoa from donors of proven fertility were isolated from semen using cervical mucus, Healonid or a direct swim-up (acting as the control). Sperm capacitation and the acrosome reaction were monitored by the chlortetracycline assay. In the mucus-treated group, there was a significantly higher percentage of capacitated spermatozoa, but a low incidence of spontaneous and A23187-induced acrosome reactions compared to the control. The use of Healonid during sperm isolation mimicked the effect of mucus relatively successfully. Since mucus and Healonid show very little chemical similarity, this finding would imply that cervical mucus exerts a physical effect during its interaction with spermatozoa, although a chemical effect cannot be completely dismissed. In conclusion, this study confirms early reports describing the ability of cervical mucus to capacitate spermatozoa but at the same time conserve sperm function. The finding that Healonid exerts an almost identical effect on spermatozoa would lend support to its use as a cervical mucus substitute during in-vitro fertility assessments and research studies.