(Of a biological process) made to occur within the living organism
The term in vivo is associated with various biological processes that are made to occur within the living organism. Literally, it means in life. It is used in contrast to the terms in vitro and ex vivo. The term in vivo is different from in vitro in a way that the former is used to refer to a biological process that is made to occur within a living organism. The latter is one in which that is made to occur outside the living organism, i.e. in an artificial environment. In vitro should not be confused though with ex vivo. The term ex vivo is associated with a biological process that is made to occur in or on a living tissue outside the organism and in an artificial environment. But similar to the two terms, in vivo is written in italics.
An example of usage is the in vivo study. An in vivo study would be one that involves a methodology wherein a biological process is made to occur within a living organism. Examples include the studies on the pathogenesis of a disease and antimicrobial effects of a newly developed drug.