In vivo

<a href="/facts/Experiment/esltM54f">Studies</a> that are in vivo are those in which the effects of various biological entities are tested on whole, living <a href="/facts/Organism/j8JkL09u">organisms</a> or <a href="/facts/Cell_(biology)/bLM9UQvy">cells</a>, usually <a href="/facts/Animal_testing/mHMf98y8">animals</a>, including <a href="/facts/Clinical_trial/q8LMr832">humans</a>, and plants, as opposed to a <a href="/facts/Biopsy/A0TdRRlr">tissue extract</a> or dead organism.
Examples of investigations in vivo include: the <a href="/facts/Pathogenesis/o9kHHK0U">pathogenesis</a> of disease by comparing the effects of <a href="/facts/Pathogenic_bacteria/X5QcVN5j">bacterial infection</a> with the effects of purified <a href="/facts/Bacterial_toxins/AXmhkDDE">bacterial toxins</a>; the development of non-antibiotics, antiviral drugs, and new drugs generally; and new surgical procedures. Consequently, <a href="/facts/Animal_testing/mHMf98y8">animal testing</a> and <a href="/facts/Clinical_trials/q8LMr832">clinical trials</a> are major elements of in vivo research. In vivo testing is often employed over in vitro because it is better suited for observing the overall effects of an experiment on a living subject. In <a href="/facts/Drug_discovery/LLdDNvjy">drug discovery</a>, for example, verification of efficacy in vivo is crucial, because in vitro assays can sometimes yield misleading results with drug candidate molecules that are irrelevant in vivo (e.g., because such molecules cannot reach their site of in vivo action, for example as a result of rapid <a href="/facts/Catabolism/CFWUdphX">catabolism</a> in the liver).
The English <a href="/facts/Microbiologist/cqEyJwNK">microbiologist</a> Professor <a href="/facts/Harry_Smith_(microbiologist)/EQkhMPKB">Harry Smith</a> and his colleagues in the mid-1950s found that sterile filtrates of serum from animals infected with <a href="/facts/Bacillus_anthracis/suoM7vhx">Bacillus anthracis</a> were lethal for other animals, whereas extracts of culture fluid from the same organism grown in vitro were not. This discovery of <a href="/facts/Anthrax_toxin/aysd8nnT">anthrax toxin</a> through the use of in vivo experiments had a major impact on studies of the pathogenesis of infectious disease.
The maxim in vivo veritas ("in a living thing [there is] truth") is a play on <a href="/facts/In_vino_veritas/WtbF2ylE">in vino veritas</a>, ("in wine [there is] truth"), a well-known proverb.

In vivo open-in-new

In vivo