In vitro (Latin: (with) in the glass) refers to the technique of performing a given experiment in a test tube, or, generally, in a controlled environment outside a living organism. In vitro fertilization is a well-known example of this. Many experiments in cellular biology are conducted outside of organisms or cells; because the test conditions may not correspond to the conditions inside of the organism, this may result in inaccurate results. Consequently, such experimental results are often annotated with in vitro, in contradistinction with in vivo .
In vitro research
This type of research aims at describing the effects of an experimental variable on a subset of an organism's constituent parts. It tends to focus on organs, tissues, cells, cellular components, proteins, and/or biomolecules. Overall, it is better suited for deducing the mechanisms of action (See in vivo for its description and respective merits). With fewer variables and perceptually amplified reactions to subtle causes, results are, generally, more discernible.
The massive adoption of low-cost in vitro molecular biology techniques has caused a shift away from in vivo research which is more idiosyncratic and expensive in comparison to its molecular counterpart. Currently, in vitro research is both vital and highly productive.