THE ORIGIN OF THE RENAL ARTERY IN MAMMALS 

 AND ITS ANOMALIES 



JOHN LEWIS BREMER 



From the Department of Anatomy, Harvard Medical School 



TEN FIGURES 



An embryological explanation of any anomaly should show 

 that from some pre-existing embryological condition both the 

 normal and the abnormal results may be derived; the agents 

 which may cause the anomaly should be simple in themselves, 

 as pressure, or the blocking of a vessel, or the relative over- 

 growth or arrest of development of certain parts, though the 

 ultimate cause of these agents will usually remain a mystery. 

 Not infrequently other vertebrates may develop normally in 

 ways which for man would be abnormal, and the citation of such 

 instances strengthens the explanation of any human anomaly. 



Certain of the anomalies of the renal arteries have been al- 

 ready satisfactorily explained. Organs which make extensive 

 migrations during growth from one position to another may 

 either retain vessels from their original location, as in the case 

 of the testis, or receive and incorporate new vessels of the region 

 invaded, as does the thyroid gland. The instances of accessory 

 renal arteries arising from the iliac arteries, from the middle 

 sacral and inferior mesenteric arteries are to be considered as a 

 persistance of the original renal vessels, normally lost, derived 

 from the plexus between the vessels mentioned, lying directly in 

 the path of the renal outgrowth from the Wolffian duct. This 

 plexus has been injected in the pig embryo of 14.0 mm. by Jei- 

 dell (1), and its influence commented on by her and by Evans (2) ; 

 it is easily traceable in embryos of other mammals of similar age. 

 Since it extends from side to side, and since the inferior mesen- 

 teric artery at this time arises by several roots from the aorta, 



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