The interaction of human spermatozoa with cervical mucus in vivo.

The interaction between human spermatozoa and cervical mucus was studied during 14 cycles of artificial insemination (AI) with a cervical cup. The concentration of spermatozoa in the inseminate was determined as were the percentage of motility, mean swimming speed, and sperm morphology. The percentage of motility, swimming speed, and morphology of spermatozoa in the mucus were determined at 1 hour and 48 hours after AI. The percentage of motile sperm was always higher in the cervical mucus than in the semen. In some cases, spermatozoa appeared to swim faster in the mucus than in the semen but in other cases the reverse was true. In all 14 cases some spermatozoa could be found in the mucus at 48 hours after AI. In general, the percentage of motility and swimming speeds of the cervical sperm remained unchanged over the 48-hour study interval. The percentage of spermatozoa with normal morphology was higher in the cervical mucus than in the semen. The alteration in the composition of the sperm population appeared to result from exclusion by the mucus of most classes of abnormal sperm. The morphology of the cervical sperm population was similar at 1 hour and at 48 hours after AI.