The fundus uteri is the body of the |uterus|, or womb, and is the portion of the female reproductive tract which serves to house and nourish the developing |embryo| and |fetus|. The |uterus| is a thick-walled organ, which connects with the fallopian tubes and extends, as the |cervix| does, into the |vagina|. During menstruation, the ~mucous~ lining of the |uterus|, called the endometrium, becomes thicker and more convoluted. This change is so that a fertilized egg, or ~zygote~, will have a thick, supportive layer to which to become attached. During the destructive, or last, phase of the |menstrual cycle|, if the egg has not been fertilized, the endometrium is shed and expelled out of the |uterus| by |contractions| of the |myometrium|, or muscular wall. These |contractions| and the subsequent shedding of the endometrial layer account for the cramps, hormonal shifts, and fluid loss during this menstrual phase. Because the endometrium is high in vascularity (density of ~blood~ vessels), its shedding causes some ~blood~ to be lost from the hemorrhaged superficial vessels. ~Blood~ accounts for the lesser part of fluid discharged, however, as most of it is mucosal lining. Following |menopause|, the |uterus| atrophies, while the |ovaries| become much less active in producing ~hormones~, making |menopause| a most dramatic physiological change in the life of the adult female.
