VERTEBRATE KIDNEY 1 



1. Examine half of a Pig's kidney. Observe that it is somewhat bean- 

 shaped in outline, with a marked depression (hilus) on one edge, in which 

 region the ureter arises. Examine the cut surface of your specimen and 

 note that three regions of the kidney can be distinguished as follows: 

 (a) an outer, darker area (cortex) containing great numbers of the mi- 

 croscopic, functional elements (Malpighian bodies) ; (6) an inner, 

 striated medullary portion (medulla) containing the uriniferous 

 tubules, and (c) the pelvis, which is really the expanded end of the 

 ureter. The uriniferous tubules of the medulla open into the pelvis at 

 the tips of the conical-shaped projections (pyramids of Malpighi), and 

 the latter are separated from each other by prolongations of the cortex 

 into the pelvis. Make a drawing of the cut surface of the kidney to show 

 the structure as observed. 



2. Examine, with the low and the high power, a prepared section of a 

 Frog's kidney and note the general arrangement, consisting of a compara- 

 tively thin area on one side which contains a number of rounded Mal- 

 pighian bodies, and a thicker area filled with the uriniferous tubules 

 which have been sectioned in various planes. Make a drawing to show 

 the general arrangement. 



3. Select a single Malpighian body and focus on it with high power. It 

 consists of (a) a spherical knot of fine blood vessels (glomerulus) con- 

 taining numerous red blood corpuscles which appear yellow in the prepara- 

 tion, and (b) a definite, surrounding membrane (Bowman's capsule) 

 which is essentially the enlarged and highly differentiated end of a uri- 

 niferous tubule. Focus on a portion of one of the uriniferous tubules 

 and note the cellular wall and central lumen. Make a drawing of a 

 Malpighian body and of a portion of a uriniferous tubule. 



» B. pp. 201-204. 



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