196 



NORMAL HISTOLOGY. 



Medullary ray contains 



Medulla contains : 



( Spiral tubules ; 



< Ends of arched collecting tubules ; 

 I Straight collecting tubules. 

 ( Descending limbs of Henle 's loops ; 

 \ The loops ; 



] Ascending limbs of the loops ; 

 v. Collecting tubules of all sizes. 



While the labyrinth is characterized by the irregular and tortuous 

 course of its tubules, the medullary ray and the medulla are dis- 

 tinguished by the longitudinal, generally parallel arrangement of their 

 components. 



The wall of all parts of the tubule consists of the basement-mem- 

 brane and the lining epithelium ; the variations in the character of 

 the latter are so numerous that it is desirable to consider each portion 

 of the tubule in detail. 



i. The capsule, the expanded and invaginated blind termination 

 of the uriniferous tubule, is lined with a single layer of large, flattened 

 epithelium, resembling endothelial plates. This covers, likewise, 



FIG. 238. 



Portions of the various divisions of the uriniferous tubules drawn from sections of human kidney : 

 A, Malpighian body ; x , squamous epithelium lining the capsule and reflected over the glomerulus ; 

 y, z, afferent and efferent vessels of the tuft ; e, nuclei of capillaries ; n, constricted neck marking 

 passage of capsule into convoluted tubule; ^..proximal convoluted tubule; C, irregular tubule; D 

 and F, spiral tubules ; E, ascending limb of Henle's loop ; G, straight collecting tubule. 



the portion reflected over the glomerulus. In ordinary preparations 

 the presence of the cells is indicated by the delicate spindle nuclei 

 seen in profile; the numerous nuclei seen within the tissues of the 



