PHYSIOLOGICAL ANATOMY OF THE KIDNEYS. 



365 





site the neck of the capsule. Once within the capsule, the arteriole breaks 

 up into five to eight branches, which then divide dichotomously into vessels 

 measuring ygVo- to y^- of an inch (8 to 17 //,) in diameter, arranged in the 

 form of coils and loops, constituting a dense, rounded mass (the Malpighian 

 coil, or glomerulus), filling the capsule. 

 These vessels break up into capillaries 

 without anastomoses. 



The blood is collected from the vessels 

 of the Malpighian bodies by veins, some- 

 times one and frequently three or four, 

 which pass out of the capsule and form 

 a second capillary plexus surrounding the 

 convoluted tubes. When there is but one 

 vein, it generally emerges from the cap- 

 sule near the point of penetration of the 

 arteriole. 



The efferent vessels, immediately after 

 their emergence from the capsule, break 

 up into a very fine and delicate plexus of 

 capillaries, closely surrounding the con- 

 voluted tubes. These form a true plexus, 

 the branches anastomosing freely in every 

 direction ; and the distribution of vessels 

 in this part resembles essentially the vas- 

 cular arrangement in most of the glands. 

 Bowman has called the branches which 

 connect together the vessels of the Mal- 

 pighian tuft and the capillary plexus sur- 

 rounding the tubes, the portal system of 

 the kidney. These intermediate vessels 

 form a coarse plexus surrounding the pro- 

 longations of the pyramids of Ferrein into 

 the cortical substance. 



The renal, or emulgent vein takes its 

 origin in part from the capillary plexus FIG. 117. Blood-vessels of the 



- . 



surrounding the convoluted tubes and in 



Dart from thp vp^plq rlistvihnTPrl in fho 

 ) VeSSeiS aiStllDUtea 111 tne 



pyramidal substance. A few branches 

 come from vessels in the envelopes of the 

 kidney, but these are comparatively un- 

 important. The plexus surrounding the 

 convoluted tubes empties into venous rad- 

 icles which pass to the surface of the kidney, and these present a number of 

 little radiating groups, each converging toward a central vessel. This arrange- 

 ment gives to the vessels of the fibrous envelope of the kidney a peculiar, stel- 

 late appearance, forming what are sometimes called the stars of Verheyn. The 

 25 



bodies and convoluted tubes of the kidney 

 (Sappey). 



1.1, Malpighian bodies surrounded by the cap- 

 sules of Muller : 2, 2. 2. convoluted tubes 

 connected with the Malpighian bodies ; 3, 

 artery branching to go to the Malpighian 

 bodies : 4, 4, 4. branches of the artery ; 6. 

 C, Malpighian bodies from which a portion 

 of the capsules has been removed : 7, 7, 7, 

 vessels passing out of the Malpighian bod- 

 ies : 8, vessel, the branches of which (9) 

 pass to the capillary plexus (10). 



