542 



THE EXCRETION OF URINE 



contain epithelium showing a prominent striation. These striations are 

 rows of granules, which run towards the lumen of the cell, becoming 

 less distinct as they approach it and apparently standing in close rela- 

 tionship to the rather prominent internal (lumen) striated border of 

 the cell. Some histologists believe that the striations at the border are 



Fig. 170. Diagram of the uriniferous tubules (C) the arteries (A), and the veins (B) of the 



kidney. 



really cilia, which are described as being immobile. The cilia are shown 

 in Fig. 171. The descending limb of Henle's loop is lined with a thin 

 pavement epithelium with large bulging nuclei. The distal convoluted 

 tubule is lined with cells not unlike those found in the proximal tubules, 

 except that the inner border is not striated. The diameter of the lumen 



