1876 



HI MAN ANATOMY. 



tli- <livisi..ns in a III..P- ..r leB marked decree, the renal lobules of the aquatic mammals being 

 unusually distinct. In some mammals ( rodents, insectivora) the entire kidney corresponds to a 

 ;..i|.ill.i. \\liile in others (elephant, horse J no distinct papilla; exist. 



FIG. 1597. 



Right kidney of new- 

 born child, showing tabula- 

 tion of surface. 



On making a longitudinal section of the fresh kidney, from its convex border 

 through the sinus, the papillae will be seen to form the free apices of conical masses, 

 the renal pyramids, the bases of which lie embedded within 

 the darker surrounding kidney-substance composing the outer 

 third of the organ. This peripheral zone, which appears darker 

 and granular in contrast to the lighter and striated renal pyra- 

 mids, constitutes the cortex; the medulla includes the conical 

 areas formed by the pyramids and partially occupies the inner 

 two-thirds of the thickness of the organ. The cortex contrib- 

 utes the bulk of the kidney, alone forming the entire surface, 

 including the lips of the hilum, and receiving and surrounding 

 the bases of the pyramids. The cortical tissue further pene- 

 trates for a variable distance between the pyramids, separating 

 the latter and in places gaining the sinus. These interpy- 

 ramidal extensions are the renal columns, or columns oj Berlin, 

 and consist of typical cortical substance. Since the branches 

 of the renal blood-vessels lie within the interlobular connective 

 tissue separating the primary divisions of the foetal organ, these vessels never enter 

 tin- kidney by passing into the papillae, but always enter at the side of these. They 

 therefc >i e sink into the renal substance within the areas occupied by the renal columns, 

 the surfaces of which directed towards the sinus are pitted by the vascular foramina. 

 Within the sinus the blood-vessels surround the calyces with coarse net-works, enter- 

 ing and emerging from the renal substance through the orifices encircling the papillae. 

 On close inspection, preferably with the aid of a hand-glass, it will be seen that 

 the cortex, including that within the renal columns, is not uniform, but is subdivided 

 by narrow striated bands, wedge-shaped 



in outline and lighter in color, into F IG - 1598. 



radially disposed darker and lighter 

 Tin- latter, consisting of groups 

 of parallel tubules, are known as the 

 medullary rays < pars radiata), since 

 they are apparently due to prolonga- 

 tions of the medullary tissue. The 

 darker tracts intervening between the 

 medullary rays form the labyrinth ( pars 

 convolula ), and appear granular, owing 

 to the tortuous character of the com- 

 ponent tubules. The labyrinth is 

 studded with bright red points mark- 

 ing the position of the vascular tufts 

 or glontfrnli, which are never present 

 within the medullary rays or the renal 

 pyramids, although found with,:-, th" 

 columns of Berlin. 



On sectioning minutely injected 



organs, it will be olis.-ryed that the 



radially coursing interlobular ar- 



on -.lining the boundary zone 



n the cortex and medulla, break 



up into smaller branches, some of whi. h 



directly touards the surface, while others change their direction and assume a. 



ar.hed horizontal course, thus producing the impression of "arcades" at the l.aseo 



I he terminal twiga " end-arteries," since anastomoses are wanting 



generally perpendicular to the exterior of the kidney and occupy the centre 



of tin- tracts .separating the medullary rays. The latter, therefore, are the axes 



Corte 



Interlobar 

 blood- vend 



Medulla 



Portion of 



sinus 



Renal 

 papilla 



Ureter 



l MCtkm Of right kidney, sliowin.u relations 

 jielvis ami its divisions to renal substance and to sinus. 



* 



