The uterus (from Latin “uterus”, plural uteri) or womb (/ w uː m /) is a major female hormone-responsive secondary sex organ of the reproductive system in humans and most other mammals.In the human, the lower end of the uterus, the cervix, opens into the vagina, while the upper end, the fundus, is connected to the fallopian tubes.It is within the uterus that the fetus develops during gestation.