TRANSVERSE SECTIONS OF A TEN MM. PIG EMBRYO 



into the crescentic urogenital sinus. Dorsal to the urogenital sinus (dorsal now being at the 

 bottom of the figure owing to the curvature of the caudal region) is a section of the rectum, 

 separated from the sinus by a curved prolongation of the ccelom. From the ends of the uro- 



Mesenrery 



Caudal //mi. 

 of Infesting 



Lower 

 limb bud 



Mewntphric 

 duct 



Notochord 



Vein in body wall 

 L.umbilical artery 



Allantois and uro- 

 genital sinus 



Rectum 



Spinal cord 



FIG. 136. Transverse section through the urogenital sinus and rectum of a 10 mm. pig embryo. X 22.5. 



Caudal limb 

 of Intestine 



Lower limb 

 bud 



ftumbilicaJ 

 artery 



Notochord 



FIG. 137. Transverse section of a 10 mm. embryo passing through the lower limb buds at the level of 

 the openings of the ureters into the mesonephric ducts. X 22.5. 



Mesentery 



ftumbilical 

 artery 



Vein 



Spinal cord 



7 ic. 138. Transverse section through the anlages of the metanephroi in a 10 mm. pig embryo. X 22.5. 



Cotton 



Atilage of 

 Metanephros 



Notochord 



