Chicken embryo: a useful animal model for drug testing?

The use of chicken embryos (CEs) as an in vivo experimental model for different pharmaceutical purposes is not a novelty. However, in recent years, the number of reports employing CE to evaluate several parameters, such as the toxicity and efficacy of drugs and/or nanosystems, has increased. Therefore, this review discusses the relevance of CE for drug testing, emphasizing the inoculation routes and the embryonic stages. The challenges to be overcome, as well as some practical recommendations to allow CE to be more explored as a promising in vivo model in drug analyses, are also highlighted.