The cyclical changes with the ovaries cause a series of cyclical changes in the female genitalia, among which the physical and chemical properties of the mucus secreted by the cervical gland cells and the amount of its secretion have obvious cyclical changes. After menstruation, the level of estrogen in the body decreases and the amount of mucus secreted by the cervical canal is small. Estrogen can stimulate the secretory function of the secretory cells. As the level of estrogen continues to rise, the amount of mucus secretion increases by the time of ovulation, and the mucus is thin and transparent, with the degree of drawing up to 10cm or more. After ovulation, influenced by the level of progesterone in the body, the mucus secretion decreases, the texture becomes viscous and turbid, the drawing degree is poor and easy to break. The content of sodium chloride in cervical mucus is the highest during ovulation. Since mucus is isotonic, the high proportion of sodium chloride inevitably leads to a corresponding increase in water, so the cervical mucus during ovulation is thin and abundant. Therefore, during ovulation, women may feel a significant increase in leucorrhea and a moist vulva, but the leucorrhea should be transparent and odorless, and there is no vaginal itching or pain. The cyclical changes of the cervical mucus can reflect the function of the ovaries at that time.