The canalization of cervical mucus in the human fertility

Canalization of cervical mucus from 31 patients at the obstetric/gynecologic clinic at the Universita Cattolica del S. Cuore in Rome, Italy has studied to determine the biochemical basis of canalization and its dependence on estrogen, to study the action on the canalization of hormones used to induce ovulation, and to correlate fern pattern and canalization. Cervical mucus was collected daily and applied to a glass slide, covered with an object cover, and allowed to dry. The typical arrangement of the dendritic crystals and the presence of channels among them were confirmed. Depending on the phase of the ovulatory cycle, the crystals differed in direction and in number. The number of channels consistently increased as estradiol levels increased during the proliferative phase. This happened in both natural and induced ovulatory cycles. The cervical mucus of patients with primary amenorrhea canalized when treated with estrogens. The channels ran parallel to each other. Yet, during the secretory phase, the number of channels fell rapidly and the channels were lined up in a crisscross fashion. This suggested that sperm penetration is dependent on the orientation of mucus crystals. Indeed in vitro studies showed that spermatozoa enter the periovulatory mucus in tightly packed files as if the mucus allowed only passage in this linear formation. The biophysical characteristics of canalization paralleled those of ferning. Moreover, like ferning, the presence of essential salts and proteins induced canalization. It is concluded that canalization can be used to accurately measure estradiol levels and thus to detect ovulation.