Definition for In vitro
From Biology Forums Dictionary
1) Literally, “in glass.” An approach to studying a process in living cells that involves isolating and purifying cellular components, outside the cell.
2) In vitro studies in experimental biology are those that are conducted using components of an organism that have been isolated from their usual biological surroundings in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments are commonly called "test tube experiments". In contrast, in vivo work is that which is conducted with living organisms in their normal, intact state, while ex vivo studies are conducted on functional organs that have been removed from the intact organism.
Common examples of in vitro experiments include work that uses (a) cells derived from multicellular organisms (cell culture or tissue culture), (b) subcellular components (e.g. mitochondria or ribosomes), (c) cellular or subcellular extracts (e.g. wheat germ or reticulocyte extracts), or (d) purified molecules in the test tube (often proteins, DNA, or RNA, either individually or in combination).
