26 THE VASCULAR SYSTEM OF THE FROG. 



a. The renal portal system. 



Trace hack the anterior ahdominal vein to the hinder end of the 

 body, where it ivill he seen to he formed, hy the union of the tivo 

 pelvic veins. Follow hack the pelvic vein of one side to the base 

 of the hind Hmh ; here it ivill he seen to he one of two branches into 

 which the femoral vein, the large vein returning blood from the 

 hind limb, divides. The other branch of the femoral vein is the 

 renal portal vein, which is to be followed to the outer side of the 

 kidney. 



1. The right renal portal vein is the dorsal branch of 



the right femoral vein : it runs forwards along the 

 outer side of the kidney and ends in numerous 

 branches in its substance. It receives the follow- 

 ing branches. 



i. The right sciatic vein, from the muscles and 

 skin of the back of the thigh, joins the 

 renal portal vein close to its commencement, 

 ' - • before it reaches the kidney. 

 ' ii. The right dorso-lumbar veins are small veins 



from the dorsal wall of the body, and, in the 

 female, from the oviduct : they join the 

 renal portal vein opposite the kidney. 



2. The left renal portal vein corresponds in its course 



and branches to the right vein. 



b. The hepatic portal system. 



This is formed partly by the anterior abdominal vein, which 

 brings to the liver blood from the hind limbs ; and ]3artly by 

 veins returning blood from the alimentary canal. 



1. The anterior abdominal vein is a median vein 

 formed by the union of the two pelvic veins, the 

 ventral branches of the femoral veins. It runs 

 forwards along the middle line of the ventral 

 body-wall to the level of the liver, where it leaves 

 the body-wall and divides into right and left 

 branches, which enter the right and left lobes of 

 the liver respectively. During its course it 

 receives the following veins, 

 i. Vesical veins, from the bladder 

 ii. Parietal veins, from the ventral body-wall. 



