TRANSVERSE SECTIONS OF A TEN MM. PIG EMBRYO 



143 



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- 



Mesentery 



Caudal l/'mb. 

 of Intestine 



Lower 

 limb bud 



Mesonephric 

 duct 



Notochord 



Vein tn body wall 

 Lumbilical after/ 



■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. 



Lowerlimb 

 bud 



/?. umbilical 

 artery 



Notochord 



__ Caudal limb 

 of Intestine 



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. 



Mesente 



Rumbilica.1 

 artery 



Coelm 



Anlaqe of 

 Metanephras 



Notochord 



Spinal cord 



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



