What is induction?

Extraembryonic membranes
Chicken embryos develop on land, and are therefore enclosed by extraembryonic
membranes in an amniotic egg.  List the four extraembryonic membranes and compare
their functions between that of a chick and that of mammals (e.g., humans).  Which
membrane carries out the same function for both?

Membrane  Chick  Human
1.

2.

3.

4.

Raw Chick Egg
Read about the raw chick egg.

What is the name of the small white disc on top of the yolk that contains the cytoplasm and the
egg nucleus?

What is the ovum composed of?

How are the shell membranes and the albumen formed around the ovum?
24-hour chick embryo
Observe the 24-hour chick embryo slide.  Make sure you can recognize the following features of
the developing embryo
[  ]  Head fold
[  ]  Neural folds / groove
[  ]  Notochord
[  ]  Somites
[  ]  Primitive streak

Does neurulation occur anteriorly or posteriorly?

48-hour chick embryo
Observe the 48-hour chick embryo slide.  Make sure you can recognize the following features of
the developing embryo
[  ]  Brain
[  ]  Heart
[  ]  Eye
[  ]  Vitelline blood vessels
[  ]  Somites

What function do the vitelline blood vessels serve?

72-hour chick embryo
Observe the 72-hour chick embryo slide.  Make sure you can recognize the following features of
the developing embryo
[  ]  Brain
[  ]  Heart
[  ]  Eye
[  ]  Vitelline blood vessels
[  ]  Limb (wings and hindlimbs) buds
[  ]  Somites
[  ]  Tail bud

Compare the location of the wing buds to the location of the hindlimb buds.
96-hour chick embryo
Observe the 96-hour chick embryo slide.  Make sure you can recognize the following features of
the developing embryo
[  ]  Different brain regions (see key)
[  ]  Heart
[  ]  Eye
[  ]  Vitelline blood vessels
[  ]  Wing buds and hindlimb buds
[  ]  Allantois

Why do you think the allantois is found near the posterior end of the embryo?