The sensitivity of chicken embryos in incubated eggs

The embryonated chicken egg is a well accepted test system in biomedical research. In connection with the discussion as an alternative to animal experiments, the sensitivity of the chicken embryo is a relevant issue. To assess the development and the reaction of the chicken embryo, the application of a standardized staging is neccessary. The sensitivity develops stepwise, beginning around day 7 of incubation. The extraembryonal blood vessel systems (yolk sac, chorio-allantoic-membrane) are not sensitive. In accordance with the 3 R"s, the embryonated chicken egg should be applied during early stages of development, to avoid a suffering of the embryo.