246 



THE LYMPHATIC SYSTEM 



him. This is continuous with the fibre-elastic terminal processes of the 

 fibromuscular trabeeulse. 



The primary trabecula? divide the parenchyma imperfectly into 

 roughly pyramidal compartments about one millimeter in diameter, with 

 three trabeculse for each lobule. This lobulation is faintly indicated by 

 surface markings. According to Mall this unit of structure, the splenic 

 lobule, is further subdivided into about ten smaller compartments by 



FIG. 250. PORTION OF SPLEEN OF CAT, SHOWING CAPSULE (ABOVE) AND Two 

 SPLENIC NODULES WITH CENTRAL ARTERIOLE. 



Between the two nodules can be seen portions of a trabecula with a blood-vessel. 



anastomosing septa, continuous with the primary trabecula?. This divi- 

 sion of the spleen into lobules, and their subdivision into lobular com- 

 partments has structural significance also from the viewpoint of the 

 blood supply. A knowledge of the microscopic structure of the spleen 

 is dependent upon an understanding of the distribution of the blood- 

 vessels. 



Blood-vessels. The splenic artery enters at the hilum, associated 

 with the splenic vein. The larger arterial branches are located within 

 the coarser trabeeulse continuous with the connective tissue of the hilum 

 and still accompanied by the larger tributaries of the splenic vein. The 



