Respiratory gases and acid-base balance in shell-less avian embryos

1. The PCO2 and PO2 levels of oxygenated and deoxygenated embryonic blood were measured in normal and shell-less cultured embryos. 2. Embryos in shell-less culture were both hypoxic and hypocapnic, suggesting that wetting the respiratory membranes and the reduction in their functional area is distorting their normal function. 3. Despite this hypocapnia, there was evidence for an increase in base excess during incubation. This suggests that plasma bicarbonate is derived from renal sources rather than by resorbing the eggshell calcium carbonate, which is, of course, absent from shell-less cultures.