124 A CYTOLOGICAL STUDY OF THE KIDNEY CELL 



and the fewer mitochondria. A. Glomerulus. B. Proximal convoluted 

 tubule. C. Distal convoluted tubule. D. Descending limb of H. L. 

 E. Ascending limb of H. L. F. Connecting segments. 



Figure 6, high power, urea fed during entire length of life, and Figure 

 7 , oil immersion, no urea fed at all, show the end stage in granular disso- 

 lution. There is no difference in size, appearance and arrangement of the 

 granules. The lumina of the tubules (proximal) are narrow and the 

 cells are high in either urea-fed and regular-diet animal. In the latter the 

 chainlike arrangement of the granules is still preserved. This configura- 

 tion has been described as the end stage of secretion. 



Figure 8, high power, urea fed just before death, and Figure 9, oil 

 immersion, urea fed during the entire life, apparently represent distinctive 

 and different types of granular dissolution. But comparing Figure 8 

 with Figure 12, it is at once apparent that these differences are only indi- 

 vidual variations of granular dissolution in the same kidney. Both these 

 pictures are from the same kidney but from different levels. In Figure 8 

 a clumping of mitochondria into larger bodies staining like mitochondria 

 is distinctly seen. In Figure 8a this has been brought out still more 

 markedly by lengthening the bellows of the camera. 



Figure 10, oil immersion, urea fed for fourteen days, shows the usual 

 variations in the height of the cells and the difference in the mitochondrial 

 density within one tubule. There is an early granular dissolution present, 

 but the rodlike arrangement is still preserved ; the picture is not different 

 from the normal. 



Figure 11, high power, urea fed during the entire length of life, shows 

 the typical batonne arrangement described for the normal and which is 

 not disturbed by intense urea feeding. 



Figure 12, high power, urea fed just before death, shows the early 

 granular dissolution which occurs normally. The brush border is just 

 faintly visible, not changed and contains a few fine granules with a mito- 

 chondrial staining reaction. 



Figure 13, oil immersion, urea fed during entire lifetime, and Figure 

 11, oil immersion, no urea fed at all, show primarily that the collecting 

 segments of the tubular apparatus is partially free from mitochondria and 

 that the few mitochondria which are present are not altered in any w r ay or 

 increased in number by prolonged urea feeding. 



Figure 1~>, oil immersion, prolonged urea feeding, and Figure 16, oil 

 immersion, no urea feeding, show that the glomerular apparatus is not 

 influenced by a severe strain such as is produced by prolonged urea 

 feeding. 



