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air cell - an empty space located at the large end of the egg; it is between the inner and outer shell membranes.
chalaza - a spiral, rope-like strand that anchors the yolk in the thick egg white. There are two chalazae anchoring each yolk; one on the top and one on the bottom. (The plural of chalaza is chalazae.) germinal disc or blastodisc - a small, circular, white spot (2-3 mm across) on the surface of the yolk; it is where the sperm enters the egg. The nucleus of the egg is in the blastodisc. inner shell membrane - the thin membrane located between the outer shell membrane and the albumin. outer shell membrane - the thin membrane located just inside the shell. shell - the hard, protective coating of the egg. It is semi-permeable; it lets gas exchange occur, but keeps other substances from entering the egg. The shell is made of calcium carbonate. thick albumin - the stringy part of the egg white (albumin) located nearest the yolk. thin albumin - the watery part of the egg white (albumin) located farthest from the yolk. vitelline (yolk) membrane - the membrane that surrounds the yolk. yolk - the yellow, inner part of the egg where the embryo will form. The yolk contains the food that will nourish the embryo as it grows.
