14 LABORATORY OUTLINES FOR EMBRYOLOGY 



layers are the thicker? Which forms the greater part of 

 the yolk, the yellow or the white yolk? 



Draw the yolk hemisphere and shade in the yellow yolk. 

 Label the parts. 



c. An Egg Incubated Three Days — Live Embryo 



Open the large end of an egg that has been incubated 

 at least three days. Notice that in whatever position 

 you turn the egg the embryo is on top. , Pour the egg into 

 a dish containing normal salt solution which is about milk 

 warm. How much of the yolk is covered by the blasto- 

 derm? Notice that immediately surrounding the em- 

 bryo is a light area. This is called the area pellucida. 

 That part of the blastoderm extending beyond the area 

 pellucida is the area opaca. The part of the area opaca 

 which contains the blood vessels is the area vasculosa. 

 What part of the area opaca is occupied by the area 

 vasculosa? What is the shape of the heart? How fast 

 does it beat? The vessels carrying the blood into the 

 heart are the vitelline veins.- How many vitelline veins 

 are there? The blood is carried from the embryo to the 

 vascular area by means of the vitelline arteries. How 

 many vitelline arteries are there? How does the blood 

 get from the heart into the vitelline arteries? What is 

 the shape of the embryo? What are the differences 

 between the yolk of this egg and the yolk of the fresh egg? 

 What are the differences in the white? 



Draw the embryo showing its relation to the yolk. Label 

 the parts. 



