Shell

Outer covering of egg, composed largely of calcium carbonate May be white or brown depending in breed of chicken

Air Cell

Pocket of air formed at the large end of the egg Caused by the contraction of the contents during cooling after laying Increases in size as egg ages

Shell membranes

Two membranes-inner and outer shell membranes surround albumen Provide protective barrier against bacterial penetration Air cell forms between these two membranes

Thin albumen (white)

Nearest to the shell Spreads around thick white of high-quality egg

Thick albumen (white)

Major source of egg riboflavin and protein Stands higher and spreads less in higher-grade eggs Thins and becomes indistiguishable from thin white lower-grade eggs

Chalazae

Twisted, cordlike strands of egg white Anchor yolk in center of egg Prominent chalazae indicate freshness

Vitelline (Yolk) membrane

Hold yolk content

Germinal disc

Yolk

Yellow portion of egg Colour varies with feed of the hen, but doesn’t indicate nutritive content Major source of egg vitamins, minerals and fat