SPLEEN. 



161 



not anastomose. For a short distance before their termination the walls 

 of these branches possess ellipsoid thickenings due to a longitudinal ar- 



Terminal vein. 



xx Sheathed artery. Pulp artery. 



Pulp vein. 



Trabecula. 



Penicillus. 



Hik 



Reticul 



Splenic nodule. 



Capsule. 



FIG. i8t. DIAGRAM OF THE BLOOD VESSELS OF THE HUMAN SPLEEN. 



At x is shown the direct connection of terminal arteries with terminal veins (the existence of! such a 

 connection has been questioned). At xx and xxx are the free endings of the terminal veins in 

 the pulp and near the nodules respectively. 



rangement of closely applied reticular fibers. These 'sheathed arteries' 

 are 6-8 p in diameter, and have been supposed to regulate the amount 

 of blood whfch enters the 

 distal portion of the artery. 

 Some authorities state that 

 this distal part connects 

 with the terminal veins, 

 meeting them at an acute 

 angle. According to others 

 such connections are infre- 

 quent, and still others 

 believe that the arteries 

 empty only into the reticu- 

 lar tissue. Numerous care- 

 ful injections have shown 

 the readiness with which the arterial blood mingles with the pulp cells. 



B 



FIG. 182. CROSS SECTION (A) AND SURFACE VIEW (B) OF 



TERMINAL VEINS FROM THE HUMAN SPLEEN. 

 e., Rod shaped endothelial cells, with projecting nuclei, n; r., 

 encircling reticular tissue ; 1., leucocytes passing between 

 the endothelial cells. (After Weidenreich.) 



