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. The hymen is irregularly shaped and has holes that allow menstrual blood to flow out of the vagina. The normal hymen itself has an opening, and the shape of the hymen in adult women varies widely. The hymen is not literally the so-called layer of membrane, it is actually a piece of very thin, very delicate connective tissue, was a ring-shaped fold-like, about 1-2mm thick. The vaginal wall of young girls is relatively thin, the ovaries are immature, the hymen is very important in blocking the invasion of germs, protecting the internal reproductive system and maintaining fertility.