In vivo studies is a research methodology involving experimentation or observation conducted within the complex, dynamic environment of a living organism. This approach investigates biological processes, disease mechanisms, or the effects of therapeutic or environmental agents in their natural physiological context, providing insights into integrated systemic responses that cannot be fully replicated by *in vitro* or *ex vivo* methods. Its significance lies in offering a higher degree of physiological relevance for translating findings to clinical or ecological applications.