In Vivo Testing refers to experiments conducted within a living organism to study the effects of a treatment, drug, or procedure. This type of testing is crucial for understanding how a substance interacts with biological systems, providing insights that cannot be obtained from laboratory studies alone. It helps researchers assess the safety and efficacy of new therapies before they are approved for human use. During In Vivo Testing, researchers may use various animal models, such as mice or rats, to simulate human responses. This approach allows scientists to observe the overall effects of a treatment in a complex living environment, including factors like metabolism and immune response, which are essential for developing effective medical interventions.