Cervical mucus

Cervical mucus

Several hundred mucus-secreting crypts in the endocervix produce 20–60 mg of cervical mucus a day, increasing to 600 mg around the time of ovulation. The viscosity and water content vary during the menstrual cycle; cervical mucus is composed of around 93% water, reaching 98% at midcycle. It contains electrolytes such as calcium, sodium, and potassium; organic components such as glucose, amino acids, and soluble proteins; trace elements including zinc, copper, iron, manganese, and selenium; free fatty acids; enzymes such as amylase; and prostaglandins. Its consistency is determined by the influence of the hormones estrogen and progesterone. In the follicular phase of the menstrual cycle, estrogen dominates and cervical mucus gradually becomes thinner, reaching its lowest viscosity at ovulation. At midcycle, around the time of ovulation—a period of high estrogen levels— the mucus is thin and serous to allow sperm to enter the uterus and is more alkaline and, hence, more hospitable to sperm. It is also higher in electrolytes, which results in the "ferning" pattern that can be observed in drying mucus under low magnification; as the mucus dries, the salts crystallize, resembling the leaves of a fern. The mucus has a stretchy character described as Spinnbarkeit most prominent around ovulation.