Label the cross section of a newly-laid chicken egg.
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.
Label a 10-day old chicken embryo in egg.
air cell - a space at the large end of the egg, between the inner and outer shell membranes.
albumin - the egg white. It provides protein and water for the embryo and protects it from microorganisms.
allantois - a sack that holds some of the embryo's waste. It is attached to the embryo near the legs.
amnion - a membrane that surrounds the embryo, protecting it from dehydration (losing water) and shock.
eggshell - the hard, protective coating of the egg. It is semi-permeable; it lets gas exchange occur, but keeps other substances from entering the egg. It is made of calcium carbonate.
embryo - the developing chick inside the egg.
eye - large and prominent on the head.
inner shell membrane - the thin membrane located between the outer shell membrane and the albumin.
leg - one of the lower limbs of the chick.
outer shell membrane - the thin membrane located just inside the shell.
tail - located at the far end (the posterior) of the embryo.
wing - one of the upper limbs of the chick.
yolk - the yellow part of the egg; it contains nourishment (food) for the embryo.
Label the Chicken Embryo
allantois - a large sack that holds some of the embryo's waste. It is located near the far end (the posterior) of the embryo, close to the leg buds.
brain - the developing brain takes up much of the head area (at the anterior) of the embryo.
eye - at this point in development, the eye consists of an eye cup and lens, and is located near the brain.
heart - the developing heart is above (anterior to) the wing buds and below (posterior to) the head.
leg bud - the beginning of the development of the of the legs are small bumps of tissue located just above (anterior to) the tail bud.
spinal cord - the developing spinal cord runs through the length of the embryo, from the brain to the tail.
tail bud - the beginning of the development of the of the tail is located at the far end (the posterior) of the embryo.
wing bud - the beginning of the development of the wings are small bumps of tissue located in the mid-section of the embryo.