Oophorectomy
Oophorectomy is the surgical removal of the ovaries of a female animal. In the case of non-human animals, this is also called spaying. It is a form of sterilization.The removal of the ovaries together with the Fallopian tubes is called salpingo-oophorectomy. Oophorectomy and salpingo-oophorectomy are not common forms of birth control in humans; more usual is tubal ligation, in which the Fallopian tubes are blocked but the ovaries remain intact.
In humans, oophorectomy is most usually performed together with a hysterectomy - the removal of the uterus.
In animals, spaying involves an invasive removal of the ovaries, but rarely has major complications other than that spayed animals tend to gain weight. Spaying is especially important for certain animals that require the ovum to be released at a certain interval (called estrus or "heat"), such as cats and dogs. If the cell is not released during these animal's heat, it can cause severe medical problems that can be averted by spaying or partnering the animal with a male.
Oophorectomy is sometimes referred to as castration, but this term is most often used to mean the removal of a male animal's testicles.