The thickness of the hymen varies from person to person. The hymen covers the vagina near the external opening and is about 1-2mm thick, with a hole in the center that allows menstrual blood to flow out of the vagina. Many people have misconceptions about the hymen, only thinking it is a layer of intact, closed film like windowpaper. In fact, the normal hymen itself has an opening, and the shape of the hymen in adult women varies greatly. Hymen is not literally the so-called layer of membrane, it is actually a very thin, very delicate connective tissue, a ring-shaped folds. The vaginal wall of young girls is relatively thin, the development of the ovaries is immature, the hymen is very important to block the invasion of germs, protection of the internal reproductive system, maintenance of fertility.