Changes in cervical mucus that prevent penetration by spermatozoa
Chantler, E.; Sharma, R.; Sharman, D.
Symposia of the Society for Experimental Biology 43: 325-336
1989
ISSN/ISBN: 0081-1386 PMID: 2701482 Document Number: 344133
After a brief review of the molecular structure of cervical mucus, the data are presented on inhibition of sperm transport through cervical mucus by polyanions and on enhancement of sperm penetration in cases of infertility due to antisperm antibodies. Cervical mucus is a gel made up of large, unbranched, glycosylated glycoprotein with highly glycosylated domains separated by hydrophobic peptide chains. Spermatozoa probably traverse the unbound water phase rather than the water bound to the macromolecules. Since mucin is a polyanion, polycations were investigated as potential vaginal spermicides. The two biguanides studies, chlorhexidine and Vantocil were both spermicidal in concentrations of 1-10 mg/ml. Their rate of entry into mucin in capillary tubes differed. Vantocil penetrated superficially and set up a barrier of inspissated mucus. Chlorhexidine entered further, with dept inversely proportional to concentration. Both biguanides increased the thickness of cervical mucus in a dose-dependent manner, as judged by dynamic storage modules, by sedimentation in analytical ultracentrifugation, and by solubility in 0.22 M thiocyanate. It was speculated that these biguanides act by altering the molecular configuration of mucin. In the presence of anti-sperm antibodies, spermatozoa observed in cervical mucus in vitro may show non-progressive mobility or immobility. The presence of auto-antibodies can be shown with Immunobeads. Binding of secretory IgA to sperm can be cleaved with bacterial protease as can binding of IgG with trypsin. By assaying the blockage of sperm by antibodies with Immunobeads and measuring penetration of sperm in donor cervical mucus, displacement of sperm antibodies could be demonstrated in 9 infertile subjects. Therefore, it might be possible to treat the ejaculate with proteases, and achieve conception by either a gamete intrafallopian tube transfer or an in vitro fertilization procedure.