air cell troubles-what's really going on...

[dancingbear]

After getting some badly damaged eggs in a shipment, with damaged air cells, I just had to get to the bottom of the "detached air cell" phenomenon. I didn't see how an air cell could detach, because it's not a separate part of the egg. It's just a gap between the shell and the membrane at the large end of the egg. It's not a separate little bag of air.

Study of the membrane in the shell of an egg I ate for breakfast shows that if you poke a hole in the membrane at the large end, into the air cell, you can flatten the menbrane against the shell. This leads me to believe that what happens is this: The membrane ruptures, and flattens against the shell, which allows the air to get out of that space, and into the white portion of the egg. Then you have a free-floating bubble of air, inside the membrane. That's all it is, a bubble.

So here's the tricky stuff. I've seen posts where people said the air cell had 're-attached'. How can a bubble attach? That's what appears to happen, but this is what I believe must must be happening:
The shells and the membranes are gas-permeable, meaning that gases, such as oxygen, water vapor, and CO2, can pass through.
As the moisture in the egg begins to evaporate, (with the egg in an upright position, big end up) the membrane at the top would start to shrink a little. As it does, it will pull away from the shell. This would let the air of that little bubble be drawn back into the space between the shell and the membrane. At this point, if the membrane isn't too badly damaged, it may indeed be possible for the egg to hatch normally, especially if it is kept upright and nearly upright, such as it would be in most auto turners, or carton-hatching. The turning by tilting the carton, (or the 'bator) would not be extreme, so it's possible the air cell could remain re-inflated. If the membrane is badly torn, this may not work. Or the bubble may continue to shift from side to side as the egg tips.

Next time you eat an egg, examine the membrane inside the shell. Pull it away from the shell in the big end. You'll see what I mean! You can't peel out an air cell. you can only break and pull out the membrane, which, undamaged, is all one piece.

 

[Akane]

I think it's just that the gap shifts or the contents of the egg shift so that the gap is not at the top. The "reattaching" is just the settling of the egg contents so the gap is kept in place again. If you set these eggs on their side the gap settles on the side of the egg. This would also explain the odd stretched air sacs that form on many shipped eggs even when the air sac is still at the big end of the egg. The contents just shifted allowing air to gather where it wouldn't. I don't think anything actually got broken or torn. If the membrane itself got torn I doubt such eggs would hatch and moisture exchange would not happen at the same rate. I have not experienced any difference in the eggs I've gotten with loose air sacs or bubbles except for the fact it's in a different place or misshapen and the chicks don't always accomplish breaking through the correct spot because of that.

 

[dancingbear]

Several of the ones in that shipment have what you're talking about, the stretched out air cells, some puffed out the membrane in more than one direction. Those might resettle, as you suggested.

Others, though, there's clearly an air bubble, just as free and loose as a bubble in a bottle of water. They've been resting for awhile now, I haven't set them because the seller very kindly offered me replacements. I'll candle them again, and see what they look like. They might not get better at all, I really don't think they will. I'm just reflecting on what might be happening with some of the eggs I've read about. If the bubble's floating around, I think there's a rupture in the membrane. If it stops floating around, the air somehow got back on the other side of the membrane.