In vitro (
Latin for
(with)in glass) means within a
test tube, or just outside a living
organism (a
cell). An example is
In Vitro Fertilization. The opposite of
in vitro is
in vivo, within a cell. As many experiments that deal with
molecular biology are conducted outside of cells, and the conditions do not necessarily represent the conditions inside the cell, results are often annotated with
in vivo or
in vitro.