in vitro

In vitro (Latin: within glass) refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments are commonly referred to as test tube experiments. In contrast, the term in vivo refers to work that is conducted with living organisms in their normal, intact state. The opposite of in vitro is ex vitro.

Common examples of in vitro experiments include:

• cells derived from multicellular organisms (cell culture or tissue culture)
• subcellular components (e.g. mitochondria or ribosomes)
• cellular or subcellular extracts (e.g. wheat germ or reticulocyte extracts)
• purified molecules in the test tube (often proteins, DNA, or RNA, either individually or in combination).