Both types of studies are used by medical researchers developing drugs or studying diseases.
Each punch in has benefits and drawbacks.
In Vivo vs.

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In Vitro: Definitions
In vitro: The term in vitro comes from the Latin “in glass.”
Researchers may use these samples to test the action of a drug or study a disease process.
In vivo: The term in vivo comes from the Latin “in (something) living.”
Clinical trials or medical studies may be performed either in vivo or in vitro.
An example would be growingcancer cellsin a dish outside of the body to study them and possible treatments.
Studies are usually done in vitro first for ethical reasons.
Researchers learn as much as possible about a drug before exposing humans to potential negative effects.
Thus, it’s hard to know what might be expected when the drug is used in vivo.
A new drug may appear to work in a dish, but not in the human body.
Therefore, the drug would not be effective when used directly in humans.
Mice and humans have important differences.
2010;160(7):15771579. doi:10.1111/j.1476-5381.2010.00872.x