riJE EARLY EMBRYOLOGY OE THE MOUSE 



47 



AUantois 



Neural groove of 

 tail fold 



Yolk-sac 



Placenta 



Neural groove 

 (posterior, open) 



Yolk-sac 



Heart 



Coelom 



Mid-gut 



Fig. 26. — Photographs (X25) of mouse embryos. A. 13 somite embryo, age 

 QJ-i^Q^i days, from inbred stock. B and C. 14 somite embryo, age 8 days 22 hours. 

 Note the greater degree of turning of this embryo, particularly in the mid-trunk 

 region, as compared with the one in A. 



