The labia majora on both sides naturally closes to cover the vaginal opening and urethral opening. Due to the action of pelvic floor muscles, the vaginal opening is closed and the front and rear walls of vagina are close to each other, which can prevent external pollution. Normal vaginal microflora, especially Lactobacillus, can inhibit the growth of other bacteria.

The internal opening of the cervix is closed, and the mucosa of the cervical canal is covered by a single layer of high columnar epithelium secreting mucus, and the mucosa forms folds, ridges or pits, thus increasing the surface area of the mucosa; The cervical canal secretes a large amount of mucus to form a jelly-like mucus plug, which becomes a mechanical barrier for upper reproductive tract infection.

Extended data:

The defense function of female reproductive system is introduced as follows:

Periodic endometrial exfoliation of women in reproductive period is also a favorable condition for eliminating intrauterine infection. The cilia of epithelial cells of oviduct mucosa swing in the direction of uterine cavity and the peristalsis of oviduct are beneficial to prevent pathogen invasion.

There are different numbers of lymphocytes, including T cells and B cells, in genital tract mucosa such as vaginal mucosa, cervix and uterus. Macrophages, complement and some cytokines all have important immune functions in local areas and play an anti-infection role. When the natural defense function is destroyed, or the immune function of the body is reduced, endocrine changes or exogenous pathogens invade.

Baidu Encyclopedia-Female Reproductive System

Phoenix Net-Under Female Reproductive System