Selective filtration of abnormal spermatozoa by the cervical mucus.

The Düsseldorf classification of spermatozoal morphology in semen is based on the spermatogenesis in the testis. So it is possible in some cases to relate a pathological finding in semen to a special disorder in the testis. We have tested the filtering effect of the cervical mucus on the various spermatozoal forms by performing a post-coital test from the upper cervical region after artificial insemination from the husband (AIH). It was found that in addition to the motility of spermatozoa their outer shape is very important for their transport through the cervical canal. Pathological spermatozoa with a rather normal-shaped head like AI and AII forms will pass the cervix almost like normal spermatozoa. In a superficial post-coital test they can be classified as 'normal'. Still, they are not able to fertilize an egg.