38 LABORATORY OUTLINES FOR EMBRYOLOGY 



dominate. What is the size of the ovary? Shape? 

 The large, colored irregularities of the ovary are the 

 recent corpora lutea. How many in each ovary? How 

 does the number compare with the number of embryos 

 in the uterus? The smaller, rounded spots that re- 

 semble blisters are Graafian follicles. Open one of 

 the Graafian follicles. What is the nature of the 

 contents? 



With a pair of scissors or scalpel remove one of the 

 enlargements by cutting mid-way between two of them. 

 Cut through the broad ligament. Open this part of the 

 uterus by cutting longitudinally the side opposite the 

 broad ligament. This cut should pass through the walls 

 of the uterus and the outer embryonic covering, the 

 chorion. In the pig, the chorion is composed of the 

 chorion proper and the wall of the allantois. From one 

 side carefully separate the chorion from the walls of the 

 uterus. Note that the inner layer of the uterine wall is 

 in folds which extend around the embryo. Also note the 

 blood vessels in this layer. What is the position of the 

 chorion with reference to these folds? Carefully sepa- 

 rate the chorion from the amnion. The amnion is 

 semitransparent and is a much thinner membrane than 

 the chroion. Note the blood vessels in the chorion. 

 (The blood vessels are in the allantoic wall of the chorion.) 

 Compare them with the blood vessels of the lining of the 

 uterus. Also note the very small blood vessels of the 

 amnion. To the ventral side of the embryo is the um- 

 bilical cord, which connects the embryo to the chorion. 



Draw the embryo in position, showing the blood vessels 



