In vitro

Refers to processes outside the living organism

In vitro means literally "in glass " (from Latin: vitrum=glass). In in vitro experiments, organisms and structures are investigated under experimental conditions rather than in their natural context. For instance, if a plant is grown on a culture medium in a Petri dish and brought to flower there, then the plant is said to be flowering in vitro.

The term has become familiar in connection with artificial fertilisation of egg cells in test tubes (in vitro fertilisation).

By contrast, in vivo (Latin: vivum=life) means that a process takes place in the living organism or under natural conditions.