26 LABORATORY OUTLINES FOR EMBRYOLOGY 



walls of the ccdome, or body cavity. How many dorsal 

 aortae are here? Is the ventral aorta present in this 

 section? Why? Between the body cavity and the 

 outside of the body on either side is a blood vessel. If 

 this blood vessel be traced through the different sections, 

 it will be seen that it connects the cardinal veins with the 

 heart. It is the duct of Cuvier. It is formed by the 

 union of the anterior and posterior cardinal veins and 

 empties into the heart near the place where the vitelline 

 veins join the heart. Identify the myocardium and the 

 endocardium. 



Draw the section, color the different germ layers, and 

 label all the parts. 



(4) Through the Embryo about Half Way between the Heart and the 

 Posterior End 



Note the beginning of the folding up of the somato- 

 pleure to form the amnion. The point on each side 

 where the lateral fold delimits the embryonic from the 

 extra -embryonic area is the lateral limiting sulcus. 

 What is the character of the mesoblastic somites? How 

 have the myotome and sclerotome been formed? On 

 the dorsal surface of the nephrotome is a thick cord of 

 cells with a small cavity in it. This is the Wolffian 

 duct or mesonephric duct. How many dorsal aortae are 

 there? Are the cardinal veins found in this section? 

 If they are present, they are called the posterior cardinal 

 veins, ,, 



.; Draw the section, color the different germ layers, and 

 label all the parts. 



