ABSTRACT
The gestation period of the chicken is only 21 days, and produces a four-chambered heart similar in structure and physiology to the human heart. Not only do the normal developmental processes occur more rapidly than in the human, but the effects of interventions during development also require less time to develop. Fertilized chicken eggs are easy to obtain and grow, requiring little more than a small, relatively inexpensive incubator to control temperature, humidity and oxygenation. The embryos are easily accessible. Investigators can either ‘window’ the egg (creating a hole in the egg shell that can be covered between observations), or grow the embryo in a shell-less culture system. Embryos can grow to hatching in a windowed setting, but in the shell-less culture system viability is poor in the later stages of development, limiting observations that require late development using this system. The fact that the embryos are not hidden within a uterus makes interventions – surgical or pharmacological – relatively simple, and many chicken embryos can therefore be treated and observed at one time.
