{( 



Ventricle !■ 



Liver 



R. ifitelline iiein 



Aortic arches 1-4 



Atrium 



'■^^ \ Vitello-umbilical vein 



L. umbilical vsin 



Fig. 88.— Ventral reconstruction of a 3.2 mm. embryo, showing vessels (His). 





Olfactory pit 

 '~Mandit)ular arch 



Conunon cardinal i 



T iteUinc vein 

 -Umbilical vein 



Umbilical vein - 



Placental attachment 



Fig. 89. — Lateral view of human embryo of 4.2 mm., showing aortic arches and venous trunks (His). 

 mx, Maxillary process; jv., anterior cardinal vein; c.v., posterior cardinal vein; ot, otocyst. 



