Ex vivo (Latin: out of the living) means that which takes place outside an organism. In science, ex vivo refers to experimentation or measurements done in or on living tissue in an artificial environment outside the organism with the minimum alteration of the natural conditions. The most common "ex vivo" procedures involve living cells or tissues taken from an organism and cultured in a laboratory apparatus, usually under sterile conditions and no alterations done for a few hours up to 24 hrs. Experiments lasting longer than this using living cells or tissue are typically considered to be "in vitro". Ex-vivo conditions allow experimentation under highly controlled conditions impossible in the intact organism, albeit at the expense of looking at the tissue in its "natural" environment. One widely performed ex vivo study is the chick chorioallantoic membrane (CAM) assay. In this assay, angiogenesis is promoted on the CAM membrane of a chick embryo outside the organism (chicken). Ex vivo studies are usually performed in vitro, although the use of these two terms is not synonymous.
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