206 



ANATOMY FOB, NUKSES. [CHAP. XVII. 



Examined under the microscope, it is seen that the urinifer- 

 ous tubules begin as little rounded dilatations, called capsules, 

 in the cortex of the kidney. These capsules are joined to the 



tubules by a constricted 

 neck, and the tubules, after 

 running a very irregular 

 course, open into straight 

 collecting tubes, which 

 pour their contents 

 through their openings in 

 the pointed ends or papil- 

 lae of the pyramids, into 

 the pelvis of the kidney. 

 (Vide Fig. 126.) 



The tubules are com- 

 posed of basement mem- 

 brane, lined throughout by 

 epithelium cells. The cells 

 vary in the different parts 

 of a tubule, some being 

 more especially adapted 

 to secretory purposes than 

 others. 



The blood-supply of the 

 kidney. For its size, the 

 kidney is abundantly sup- 

 plied with blood." The 

 renal artery, coming di- 

 rectly from the aorta, 

 divides as it enters the 

 hilus of the kidney into 



FIG. 124. VASCULAR SUPPLY OF KIDNEY. 

 (Cadiat.) a, part of arterial arch; 6, arterial 

 branch passing upwards through the cortex ; 

 c, glomerulus; d, efferent vessel ; e, meshwork 

 of capillaries; /, straight arterial vessels of 

 medulla; g, venous arch; h, straight veins of 

 medulla. 



branches, which, slipping 

 around the pelvis, pass 

 inwards between the pyra- 

 mids. On reaching the 

 boundary line between the 



cortex and the medulla, the branches divide laterally to form 

 more or less complete arches (the veins also divide in a similar 

 manner to form venous arches). From the arterial arches ves- 

 sels pass upwards through the cortex, giving off at intervals 



