Abstract:
The avian embryo has a long history of use as a model system for the study of morphological and physiological development.  Properties of avian eggs that make them good developmental models include the large range of functional maturity at hatching and the ability to easily manipulate the environment in which the egg is incubating.  The chicken embryo develops over a 20 day incubation period.  During the first 19 days of incubation, the embryo relies on the chorioallantoic membrane for gas exchange.  The embryo begins the hatching process on day 19 which involves internal pipping, external pipping, and finally hatching.  Our lab uses the chicken embryo to study the development of the cardiovascular system, specifically the ductus arteriosi.  The ductus arteriosi are a pair of blood vessels in the avian embryo which allow blood to bypass the non-ventilated lungs.  Upon initiation of lung ventilation these blood vessels must close.  Closure appears to be stimulated by increased oxygen in the blood due to increased lung ventilation during external pipping.  The properties of the avian model system will allow us to explore questions regarding the effect of environmental stress during development on the ductus arteriosus that cannot be addressed with typical mammalian models.

Full Text Article

• Introduction
• Why Study Development Using the Avian Egg?
• Basic Physiology of the Developing Avian
• A Special Vessel: the Ductus Arteriosus
• Conclusions
• References
• Figure 1: Changes in respiration in the developing human and bird
• Figure 2: Cross-sections of the ductus arteriosus and bird
• Table 1: Comparison of oxygen and carbon dioxide levels in the chicken embryo and fetal lamb