MEMBRANES
SHELL MEMBRANES: just inside the shell are two shell membranes. inner and outer. After the egg is laid and it begins to cool, an air cell forms between these two layers at the large end of the egg.

VITELLINE MEMBRANE: This is the covering of the yolk. Its strength protects the yolk from breaking. The vitelline membrane is weakest at the germinal disc and tends to become more fragile as the egg ages. -see Air Cell, Composition, Formation, Grading