Aortic arches 7-4 



Atrium 



V Hello-umbilical vein 



L. umbilical vein 



R. vitelline vein 



FIG. 83. Ventral reconstruction of a 3.2 mm. embryo, showing vessels (His). 



FIG. 84. Lateral view of human embryo of 4.2 mm., showing aortic arches and venous trunks (His). 

 mx, Maxillary process; mn, mandibular arch; d.C., common cardinal vein; jv., anterior cardinal vein; 

 C.D., posterior cardinal vein; v.v., vitelline vein; u.a., umbilical artery; u.v , umbilical vein; all., allantois; 

 pi., placental attachment of body-stalk; olf., olfactory pit; ot, otocyst. 



