THE KIDNEYS. 



1883 



Blood-vessel 



pj'o' B-fi Descending 

 '- limb of loop 



membrana propria almost as far as the termination of the canal. At this point the membrane 

 fades away and the epithelium of the duct becomes continuous with that clothing the surface of 

 the papilla and lining the pelvis of 

 the kidney. FIG. 1608. 



It is evident that the num- 

 ber of Malpighian bodies and uri- 

 niferous tubules proper is greatly 

 in excess of the larger collecting 

 tubes, each papillary duct repre- 

 senting the termination of an elab- 

 orate system of dividing canals as 

 far as the connecting tubules, from 

 which point the true uriniferous tu- 

 bules complete their tortuous path 

 without further subdivision. 



The Supporting Tissue. 

 The interstitial stroma holding in 

 place the tubules and the blood- 

 vessels consists of a net-work of 

 modified connective tissue, or re- 

 ticulum, which has been shown 

 by Mall to withstand pancreatic 

 digestion and to form a continu- 

 ous framework throughout the 

 kidney. The stroma is most abun- 

 dant along the paths of the in- 

 terlobular and the larger blood- 

 vessels, from the adventitia of 

 which delicate trabecula:; extend 

 in all directions to form the meshes 

 lodging the tubules, smaller ves- 

 sels, and capillaries. Within the 

 cortex the supporting tissue is meagre, being best developed along the interlobular vessels and 

 around the Malpighian bodies. According to Mall, the membrana propria of the tubules is 

 resolvable into delicate net-works of reticulurn directly continuous with the surrounding stroma, 

 the general arrangement of which corresponds to the disposition of the tubules. Within the 

 medulla the interstitial tissue is much more abundant than in the cortex, its amount increasing 

 towards the apex of the papilla, in which location considerable tracts of comparatively coarse 

 stroma-fibres separate the papillary ducts. At the surfaces of the divisions of the renal substance 



limbs of Henle's loops 



1 pyrai 

 , blooc 



]-vessels, 



; large collecting tubules, 

 1 stroma. X 130. 



FIG. 1609. 



Section across upper part of renal pyra- 

 mid, showing groups of blood-vessels sur- 

 rounded by uriniferous tubules. X 50. 



FIG. 1610. 



Space for blood-vessel 



Supporting stroma-tissue of kidney after 

 pancreatic digestion ; spaces lodged tubules 

 and blood-vessels. X no. 



the interstitial tissue is continuous with the investing fibrous capsule, the interlobar septa, or the 

 lining of the pelvis, as the case may be. Not only the blood-vessels, but likewise the nerve- 

 trunks and the lymphatics are provided with sheaths of the renal stroma. 



