Studies performed with cells or biological molecules studied outside their normal biological context; for example proteins are examined in solution, or cells in artificial culture medium. Colloquially called “test tube experiments”, these studies in biology and its sub-disciplines are traditionally done in test-tubes, flasks, petri dishes etc.
They now involve the full range of techniques used in molecular biology such as the so-called omics. Studies that are conducted using components of an organism that have been isolated from their usual biological surroundings permit a more detailed or more convenient analysis than can be done with whole organisms. In contrast, in vivo studies are those conducted in animals including humans, and whole plants.