Effects of drilling holes into the air cell of incubated goose eggs on distribution of oxygen partial pressures under the shell

1. The purpose of this work was to measure changes in oxygen pressure in th e air cell, and under the eggshell (PAO2) of pre-pipping goose eggs before and after drilling holes into the air cell. 2. Drilling a 0.6 mm(2) (diameter of 0.9 mm) hole into the air cell caused an increase in air cell PAO2 of about 10 Torr. The rate of increase attenua ted as hole area increased and reached about 21 Torr when the drilled area was 8.5 mm(2). 3. The PAO2 OF intact eggs was not equally distributed under the shell. It was high in the air cell, area (108 Torr) and decreased towards the pointed end (86 Torr). 4. The increase in PAO2 after drilling a 4.9 mm(2) hole was high in the air cell (18 Torr) and decreased with distance, becoming non-significant at th e pointed end. The significant increase in PAO2 after drilling was limited to a distance of up to 38 mm along the shell from the edge of the air cell. This indicates that lateral diffusion in the shell membranes under the she ll is limited. 5. Drilling a hole of 3.5 to 4.9 mm(2) was enough to increase air cell PAO2 in most of the eggs above the critical value of 100 Torr for hatching succ ess. The increase in PAO2 was limited to about half the area of the shell a nd the average increase in PAO2 was 6.3 Torr (equivalent to a 0.9% increase in ambient O-2). However, the blood perfusing chorioallantoic areas furthe r away from the air cell edge may not be fully saturated with O-2 and may n ot be sufficient to compensate Fully for the low O-2 availability caused by low eggshell conductance.