The uterus (the Latin "uterus", plural uterus) or womb is an important female hormone that responds sexual organ's reproductive most mammals, including humans. One end, cervix, open in the vagina, while the other is connected to 1 or 2 fallopian tubes, depending of the species. It is within the uterus that the fetus develops during gestation, usually developing completely in mammals placental such as human beings and partially in marsupials such like kangaroos and opossums. Two uteruses usually form initially in a female fetus, and in placental mammals that may melt partially or completely in a single uterus depending of the species. In many species with two uteruses, only one is functional. Humans and other primates superiors like chimpanzees, along with horses, usually have a single uterus completely melted, though in some individuals the uteri may not have a complete fusion. In English, the term uterus is used consistently within professions medical and allied, while the term matrix Germanic derivative is most common in everyday usage.
La most animals that lay eggs, as birds and the reptiles, including species most ovoviviparous, have a oviduct instead of a uterus. Please note however, that the recent investigation on the biology of the viviparous (not just ovoviviparous) eslizón Trachylepis ivensi has revealed the development of a close analog to the development of the placenta of mammals eutherian.
In the monotremes, mammals that lay eggs, i.e. el ornitorrinco and equidnas, either the term uterus or oviduct is used to describe the same organ, but the egg no develops a placenta inside the mother and therefore not receive more food after the formation and fertilization.
Los marsupials have two uteruses, each of which connects with the vagina lateral and that both use one third, "Vagina" center which functions as the birth canal. Embryos marsupials form a choriovitelline "placenta" (which can be thought as something between an egg monotreme and a "true" placenta), in which the egg yolk without Output supplies a large part of nutrition of the embryo, but also adheres to the uterine wall and takes nutrients from maternal blood.