CHAPTEK XVII. 

 DISEASES OF THE UEINAEY SYSTEM. 



DISEASES OF THE KIDNEY. 



Congenital Abnormalities. The renal bud, arising as it does 

 from the dorsal aspect of the Wolffian duct near the cloaca, may 

 be said to have a pelvic origin. In the process of growth it 

 assumes a position behind the peritoneum of the lumbar region. 

 The kidney sometimes remains in the pelvis between the rectum 

 and bladder, in other instances it lies on the sacral promontory 

 below the bifurcation of the aorta, or may be found on the 

 sacro-iliac synchrondrosis, on the venter of the ilium, or abnor- 

 mally low in the lumbar region. In all such cases the kidney is 

 firmly fixed and the vessels are short, being derived from the 

 arterial and venous trunks in the immediate neighbourhood, the 

 vessels wandering into the organ during development. Fusion 

 of the renal buds may occur, giving rise to a solitary kidney, 

 which is usually of abnormal shape. The horse-shoe form is 

 commonest, the kidneys being united across the spinal column 

 by their lower poles. Occasionally the fused renal mass lies on 

 one or other side of the spine. 



The suprarenal bodies do not participate in displacements of 

 the kidneys, but are usually found in their normal positions. 



Congenital cystic kidneys consist of a congeries of retention 

 cysts, which largely replace the renal substance. The cysts 

 vary up to three-quarters of an inch in diameter, and are 

 supposed to be cystic dilatations of Wolffian remanants included 

 in the kidney substance proper. Minute masses of tissue having 

 the structure of the suprarenal body are also occasionally 

 found embedded in the kidney. These are known as " adrenal 

 rests." 



