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. Its use in a hysterectomy when there are no other health problems is somewhat controversial.
In animals, spaying involves an invasive removal of the ovaries, but rarely has major complications; the superstition that it causes weight gain is not based on fact. 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 that term is most often used to mean the removal of a male animal's testicles.
Securities are tradeable interests representing financial value. They are often represented by a certificate. They include shares of corporate stock or mutual funds, bonds issued by corporations or governmental agencies, stock options or other options, other derivative securities, limited partnership units, and various other formal "investment instruments." Banknotes, checks, and some bills of exchange do not fall into this category.
New issues of securities, including what is commonly known as an IPO, or Initial Public Offering, for new stock issues, are offered on the primary market. Securities that have already been issued may also be traded; this trading is called the aftermarket or secondary market. Secondary markets often consist of what is called an exchange to facilitate the meeting of buyers and sellers. They are often referred to as a stock exchanges, even though there are exchanges such as the Chicago Board of Options Exchange where no stocks are traded.
In the United States, the offer and sale of securities is either registered pursuant to a registration statement that is filed with the Securities and Exchange Commission (SEC) or are offered and sold pursuant to an exemption therefrom. Dealing in securities is heavily regulated by both the federal authorities (chiefly SEC) and state authorities. In addition the industry is heavily self policed by Self Regulatory Organizations (SRO's), such as the NASD or the MSRB.
Due to the difficulty of creating a general definition that covers all securities, the SEC attempts to define "securities" exhaustively (and not very precisely) as: "any note, stock, treasury stock, security future , bond, debenture, certificate of interest or participation in any profit-sharing agreement or in any oil, gas, or other mineral royalty or lease, any collateral-trust certificate , preorganization certificate or subscription, transferable share , investment contract , voting-trust certificate , certificate of deposit for a security, any put, call, straddle, option, or privilege on any security, certificate of deposit, or group or index of securities (including any interest therein or based on the value thereof), or any put, call, straddle, option, or privilege entered into on a national securities exchange relating to foreign currency , or in general, any instrument commonly known as a "security"; or any certificate of interest or participation in, temporary or interim certificate for, receipt for, or warrant or right to subscribe to or purchase, any of the foregoing; but shall not include currency or any note, draft, bill of exchange , or banker's acceptance which has a maturity at the time of issuance of not exceeding nine months, exclusive of days of grace, or any renewal thereof the maturity of which is likewise limited." - Section 3a item 10 of the 1934 Act.