The Chicken Embryo Model: A Novel and Relevant Model for Immune-Based Studies

Abstract

Dysregulation of the immune system is associated with many pathologies, including cardiovascular diseases, diabetes, and cancer. To date, the most commonly used models in biomedical research are rodents, and despite the various advantages they offer, their use also raises numerous drawbacks. Recently, another in vivo model, the chicken embryo and its chorioallantoic membrane, has re-emerged for various applications. This model has many benefits compared to other classical models, as it is cost-effective, time-efficient, and easier to use. In this review, we explain how the chicken embryo can be used as a model for immune-based studies, as it gradually develops an embryonic immune system, yet which is functionally similar to humans'. We mainly aim to describe the avian immune system, highlighting the differences and similarities with the human immune system, including the repertoire of lymphoid tissues, immune cells, and other key features. We also describe the general in ovo immune ontogeny. In conclusion, we expect that this review will help future studies better tailor their use of the chicken embryo model for testing specific experimental hypotheses or performing preclinical testing.

Keywords: chick embryo; chicken; chicken embryo; chorioallantoic membrane; egg; immunology; ontogeny; preclinical model.

Figure 1

Summary of the similarities and differences between the human and the chicken immune systems. * Present in both species, with a lower contribution in chickens. † Present in both species, with a lower contribution in humans.

Figure 2

Observed immune system features during chicken embryogenesis. Caveat: This figure summarizes observations reported in the scientific literature. They correspond to specific studies each performed at specific time points and do not represent the extent of immune system features over the embryogenesis. Thus, it cannot be interpreted as an accurate depiction of the immune system development in ovo, since most papers do not cover the entire development period.