NORMAL HISTOLOGY. 



posed. In the adult human organ all traces of such divisions have 

 usually disappeared ; during foetal life, however, the lobules are dis- 

 tinctly seen, a condition which is permanently retained in many of 

 the lower animals. 



The medulla is occupied by 8-18 striated conical Malpighian 

 pyramids, the apices of which correspond to the papillae, while their 

 bases occupy the line of juncture between the cortex and the medulla. 



Each pyramid exhibits 



FlG - 2 35- alternating light and dark 



C ,,.. . striae, these markings 



being respectively the 

 uriniferous tubules and 

 the blood-vessels. The 

 masses of the organ ex- 

 tending between the sides 

 of the Malpighian pyra- 

 mids as far as the pelvis 

 constitute the columns 

 of Bertini, and are trav- 

 ersed by the large blood- 

 vessels. 



At certain points along 

 their bases the striae of the 

 Malpighian pyramids are 

 continued into the cortex 

 as slender, tapering bun- 

 dles of parallel tubules, 

 which form the medul- 

 lary rays, or pyramids 

 of Ferrein. By the 

 penetration of these bun- 

 dles the cortex is sub- 

 divided into the med- 

 ullary rays and the 

 labyrinth, the latter ap- 

 propriately so named on 

 account of the great tortuosity of the component uriniferous tubules. 

 The dark-red points irregularly studded over the labyrinth indicate 

 the position of the Malpighian bodies. In sections parallel to 

 the free surface the medullary rays appear as groups of tubules sur- 

 rounded by the labyrinth on all sides. 



The blood-vessels of the labyrinth are enveloped in connective 

 tissue, which latter represents the interlobular tissue of other 

 glands and the boundaries of the primary lobules. The secreting 



Section of human kidney, including cortex and portion of 

 medulla, showing general arrangement of tissues. Cortex 

 (C) is imperfectly subdivided by bundles of parallel tubules 

 constituting the medullary rays (m) ; between these lies the 

 labyrinth (/) containing the Malpighian bodies (x) ; in places 

 (*') the glomerulus has fallen out, leaving the empty capsule ; 

 b and v, sections of blood-vessels. 



