What are the four types of animal models used in experimental research?

• A. Genetic, Environmental, Invasive (Nervous), Invasive (Bodily Parts)
• B. Species, Strain, Age, Sex
• C. In Vivo, In Vitro, Ex Vivo, In Silico
• D. Natural, Artificial, Hybrid, Synthetic

Answer: (A)

Understanding how researchers build animal models often comes down to the method used to create or induce the condition being studied. The four types captured here reflect the main ways this is done in practice: genetically altering the animal to carry disease-relevant mutations or deletions; changing the animal’s environment to elicit behavioral or physiological changes that model human conditions; performing invasive procedures that affect the nervous system to study brain function or pathology; and invasive procedures that affect other bodily parts to model organ injury or dysfunction. Each category represents a different route to reproduce aspects of a human condition in animals: genetic models mimic inherited risk, environmental models simulate how experiences shape outcomes, nervous-system invasive models isolate neural mechanisms, and bodily-parts invasive models focus on organ-level damage. Other options refer to animal characteristics or to broad research methods rather than to specific model types.