Hen's eggs with retarded gas exchange. I. Chrorioallantoic capillary growth

The diffusing capacity of the hen's egg for carbon monoxide (D τ CO ) increases during incubation, reflecting the development of the chrioallantoic circulation. Previous work showed that the increase in D τ CO could be diminished by incubating eggs in a 60% oxygen environment. The present work explored the effects of impeding gas exchange on the development of D τ CO . Half the shell area was covered during incubation by a removable neoprene membrane which limited D τ CO by approximately 20%. No difference could be detected between the D τ CO values (measured with the membrane removed) of these eggs and control eggs in incubated in the same 21% oxygen environment without a neoprene membrane. We conclude that the development of the chorioallantoic circulation is at its maximum under normal conditions of incubation and cannot be accelerated by restricting gas exchange.