Effect of reducing the shell area on the respiratory properties of chicken embryonic blood.

Abstract In hen eggs, the effect of reducing the shell area available for respiration on gas exchange in chicken embryonic blood has been studied. Gas exchange through the shell over either the air space or the narrow end was blocked by coating about one-fourth of the total shell surface with epoxy cement. P O 2 , P CO 2 , pH and Hct in the chorioallantoic venous blood were simultaneously measured at days 10, 12, 14,16 and 18. [HCO − 3 ], total-CO 2 , content in plasma and base excess were graphically determined. The respiratory parameters determined were significantly different between control group and coated groups, while the difference between the two coated groups was not statistically significant. The hatchability in coated groups was very poor and a few embryos died even after reaching the air by pipping. Thus, it appears that such embryos near hatching encounter physiologically critical limits concerning blood gas metabolism. No difference could be established in the contribution to the gas exchange between the shell area of the narrow end and the area over the air space.