[Cervical mucus. III. Physiological roles].

The first part of this large review on the bibliography of cervical mucus was concerned both with the mechanism and the determinism ensuring its secretion. A second paper reviewed the present knowledge on chemical, physical ultrastructural characteristics of cervical mucus. This paper, the last part of the review, will be concerned with the different functions of the mucus ensuring synchronisation and encounter of the germ cells. From a physiological point of view, the following properties may be ascribed to the cervical secretion: - protection of sperm from the hostile environment of the vagina, and from being phagocytized along the cervical canal ; - cyclic receptivity to sperm penetration at or near ovulation and interference with entry at other periods ; - filtering effect on sperm cells; - possible intracervical sperm storage ; - supplementing the energy requirements of sperm ; - protection of the uterine cavity against bacteria.