189 



Nachdruck verboten. 



Persistence of the embryonic Arrangement of the post-renal 

 Part of the Cardinal Veins. 



By C. J. Patten, M. A., M, D., So. D., Professor of Anatomy, 

 Sheffield University. 



With one Figure. 



The condition here figured I found in a male subject, aged forty. 

 The two large veins on either side of the abdominal aorta are each 

 about three-quarters the calibre of the normal inferior vena cava. 

 They take the place of the post-renal segment of this vessel, but 

 above the level of the renal veins they unite to form the pre-renal 

 part of the inferior vena cava, which when traced upward presents 

 the normal relations to the liver, diaphragm, pericardium, and heart, 

 except that its intra-pericardial course appears somewhat longer than 

 usual. The two vessels in question are of equal size, and almost of 

 equal length, and are not connected by the "transverse iliac vein", 

 which in the embryo, as development proceeds, becomes the terminal 

 portion of the left common iliac vein ^). The presence of these two 

 vessels may be indeed regarded as persistence, equally on the two sides 

 of the embryonic condition of the posterior cardinal veins before the 

 period of the establishment of the common iliac veins. This embryonic 

 <;ondition may be observed persisting as far upwards as the point 

 where the pair of segmental veins which here have become permanently 

 the renal veins, are seen entering the cardinals. The right cardinal, 

 formed by the union of the external and internal iliacs of its own 

 side, measures, from its origin to the point of junction with its renal 

 yein, 13.75 cm. 



The left vessel measured similarly, is 13.25 cm in length, and 

 also arises by the union of its respective internal and external iliac 

 vessels. 



The relations of the iliac veins to the iliac arteries are as fol- 



1) It may however be stated that several small transverse veins 

 (not indicated in the illustration) connected the cardinals at irregular 

 intervals. 



