KIDNEYS. 



71 



of the ilium ; the anterior surface is convex, the posterior concave, and 

 presents a deep notch, the hilum. 



The kidney is surrounded by a thick layer of fat, beneath which is the 

 fibrous coat, thin and smooth, composed of dense white fibrous tissue with 

 which are intermingled elastic fibres. It is adherent to the surface of the 

 organ, but can easily be removed by dissection. 



The Substance of the Kidney is dense, but friable ; upon making a 

 longitudinal section, and dividing it, there is presented a cavity, \he pelvis, 

 lined by the proper fibrous coat and occupied by the expanded portion of 

 the ureter. 



The kidney exhibits two structures, viz. : 



1. An external or cortical portion, about */ of an inch in diameter, of a 

 reddish color, and somewhat granular. 



2. An internal or medullary portion, of a dark red 

 color, arranged in the form of pyramids, the bases 

 of which are directed toward the cortical portion, 

 and the apices toward the pelvis, into which they 

 project, and are covered by the calyces. 



The Cortical portion of the kidney consists of a 

 delicate matrix containing an immense number of 

 tubules, having a markedly convoluted appearance, 

 and interlacing in every direction (the tubules of 

 Ferrein). Throughout its structure are numerous 

 ovoid bodies, the Malpighian bodies, which are the 

 flask-like terminations of the convoluted tubules ; 

 these tubes are composed of a delicate homogeneous 

 membrane lined by nucleated cells. After pursuing 

 a most intricate course in the cortical portion, they 

 become narrower and form loops which dip into the 

 pyramidal portion (Henle's tubules), returning upon 

 themselves, to finally terminate in the straight tubes 



of the pyramids. 



Diagrammatic exposi-* 



The Malpighian bodies, the dilated extremities tion of the method in 

 .. f A. v , , , , , 



the convoluted tubes, consist of a little sac (the 



capsule of Miiller), which is ovoid in shape, measuring 



about the ^1^ of an inch in diameter, and contains a 



tufted mass of minute blood vessels, over the surface of which is reflected 



a layer of cells. 



Medullary Substance. The conical masses, the pyramids of Mai- 



which the uriniferous 

 tubes unite to form 



