Meeting Abstract

P2.110  Jan. 5  Respiratory and cardiovascular interactions during internal pipping in chicken embryos SBONG, SM*; DZIALOWSKI, EM; University of North Texas; University of North Texas stephaniesbong@hotmail.com

During the final days of incubation, the developing avian embryo employs a dual gas exchange system at the chorioallantoic membrane (CAM) and lungs. Lung ventilation begins with internal pipping when the embryo breaks the air cell with its beak. In the time between internal pipping and hatching, lung ventilation increases and CAM gas exchange decreases. Our project focused on the interaction between the respiratory and cardiovascular systems in response to changes in oxygen levels at the air cell or the rest of the egg. By measuring lung and CAM oxygen consumption independently we found that decreasing air cell oxygen content from 12% to 5% O₂ resulted in a decrease in lung O₂ exchange of -0.16 � 0.06 ml O₂ min^-1 and an increase in CAM O₂ exchange of 0.10 � 0.05 ml O₂ min^-1; an increase to 21% O₂ in the air cell produced an opposite response of similar magnitude. When the egg was treated with hypoxia (15% O₂) and hyperoxia (30% O₂), a similar pattern resulted. Subsequently, the air cell and egg were treated simultaneously with apposing oxygen levels, exhibiting compensation at the complementary gas exchange sites. Blood flow increased significantly to the lungs during hyperoxic lung exposure and significantly decreased during hypoxic lung exposure. These results demonstrate the internally pipped embryo�s ability to control the site of gas exchange between the CAM and lungs by means of altering blood flow between the two organs.