Molecular arrangement of cervical mucus: a reevaluation based on laser light-scattering spectroscopy.

Evidence obtained from laser light-scattering spectroscopy suggests that the molecular arrangement of cow estrous cervical mucus is an ensemble of entangled random-coiled macromolecules rather than a cross-linked macromolecular network, the model heretofore widely accepted. This new model can account for the following phenomena: (1) The viscoelastic properties of the estrous mucus and human mid-cycle cervical mucus are the result of the way in which the glycoproteins are entangled. Variations of these properties during the reproductive cycle may simply be due to changes in the water content of the cervical mucus. (2) Penetration of spermatozoa in mucus may be entirely mechanical without involving any kind of enzymatic lysis of cross-links (this is supported by changes in the pattern of spermatozoa flagellation during sperm penetration of cervical mucus as shown in motion picture films). (3) The orientation of spermatozoa in the cervical muscus need not be due to the presence of 'channels' between micelles but simply to an artifact, the stretching or flow of the mucus, which orients the entangled macromolecules and thus facilitates the penetration of spermatozoa in an axis parallel to them.