Fig. 175. Pig embryo 10-mm. 

 long. Note the well-developed 

 head, which contains the five pri- 

 mary divisions of the brain (Fig. 

 177). In the neck region visceral 

 grooves may be seen. The limb buds 

 and tail bud are well developed. 

 The body wall has been cut away 

 to reveal the heart, the liver, and 

 the large mesonephros. 



SPINAL GANGLION 

 MOTOR REGION 



MESONEPHROS 



MOTOR REGION 

 SPINAL GANGLION 



FlG. 176. Spinal cord and spinal ganglia of pig and human embryos. 



Fig. 177. A section through the five primary divisions of the brain of 

 pig embryo. 



271 



