30 LABORATORY OUTLINES FOR EMBRYOLOGY 



What is the shape of the lens? Of how many layers of 

 cells is it composed? Identify all the blood vessels. 

 Are the Wolffian ducts present? If present, where are 

 they? What has become of the mesoblastic somites? 

 The fore-gut may have two diverticula, one on either side 

 of the ventral part. These are the lung-buds. 



Draw the section, color the different germ layers, and 

 label all the parts. 



(3) Through the Olfactory Pits 



Where are the olfactory pits with reference to the fore- 

 brain? Does this section pass through the mid-brain? 

 Identify all the blood vessels in the section. The rather 

 elongated ventral evagination from the fore-gut is the 

 first liver diverticulum. Find the Wolffian ducts. Near 

 the Wolffian ducts are one or more rather thickened 

 tubules. These are the beginnings of the Wolffian 

 bodies. It will be seen that the gut and the tissue imme- 

 diately surrounding it are connected to the body dor- 

 sally by a neck of tissue. This neck of tissue is the dorsal 

 mesentery. There is also a short neck of tissue ventral 

 to the gut. This is the ventral mesentery. The thick en- 

 ings of the body wall to the side of the posterior part of 

 the body cavity are the fore-limb buds. 



Draw the section, color the different germ layers, and 

 label all the parts. 



(4) Through the Allantois Where it is Connected with the Hind-gut 



The allantois is a bladder-like evagination from the 

 ventral side of the posterior part of the hind-gut. What 



