PRIMITIVE BLOOD VASCULAR SYSTEM 



273 



A .v.c.v. 



FIG. 268. A , The development of the vertebral artery in a rabbit embryo of twelve days (Hochstetter 

 from McMurrich). /// AB to VI AB, branchial arch vessels; Ap, pulmonary artery; A.v.c.b. and 

 A.V.C.V., cephalic and cervical portions of vertebral artery; A.S., subclavian artery; C.d. and C.v., in- 

 ternal and external carotid arteries. I.Sp.G., spinal ganglion. B, Arterial system of an embryo of 

 10 mm. (His). Ic, internal carotid; P, pulmonary artery; Ve, vertebral artery; III to VI, persistent 

 aortic arches. 

 18 



