204 BLOOD-VESSELS OF THE SPLEEN. 



mixed with numerous fine fibres of elastic tissue and some non-striped 

 muscular fibres. 



Reticulum. Within the meshes of the trabecular framework there is 

 dispersed a very delicate net-work (reticulum) of adenoid tissue (Billroth), 

 which, with the other coloured elements that fill up the meshes, con- 

 stitute the splenic pulp (Fig. 89). The reticulum is continuous with the 

 fibres of the trabeculae. [If a fine section of the spleen be " pencilled " 

 in water, so as to remove the cellular elements, the preparation presents 

 much the same characters as a section of a lymph-gland similarly 

 treated, viz., a very fine net-work of adenoid tissue, continuous with, 

 and surrounding the walls of, the blood-vessels. The spaces of this 

 tissue (His) are filled with lymph and blood-corpuscles.] 



The Pulp is a dark reddish-coloured semi-fluid material, which may 

 be squeezed or washed out of the meshes in which it lies. It contains 

 a large number of coloured blood-corpuscles, and becomes brighter 

 when it is exposed to the action of the oxygen of the air. 



Blood-Vessels and Malpighian Corpuscles. The large splenic artery 

 splits up into several branches before it enters the spleen, and it is accom- 

 panied in its course by the vein. Both vessels and their branches are 

 enclosed in a fibrous sheath, which becomes continuous with the trabeculae. 

 The smaller branches of the artery gradually lose this fibrous investment, 

 and each one ultimately divides into a group or pencil of arterioles (PENI- 

 CILLI) which do not anastomose with each other. [Thus each branch is 

 terminal a condition which is of great importance in connection with 

 the pathology of embolism or infarction of the vessels of the spleen.] At 

 the points of division of the branches of the artery, or scattered along 

 their course, are small oval or globular masses of adenoid tissue about 

 the size of a small millet seed (^ to -^ inch in diameter) the MAL- 

 PIGHIAN CORPUSCLES. [These bodies are visible to the naked eye as 

 small, round, or oval white structures, about the size of millet seed, in 

 a section of a fresh spleen. They are very numerous [7,000 in man 

 (Sappey)] and are readily detected in the dark reddish pulp. 

 We must be careful not to mistake sections of the trabeculae for 

 them. These corpuscles consist of adenoid tissue, whose meshes 

 are loaded with lymph-corpuscles, and they present exactly the same 

 structure as the solitary follicles of the intestine (compare Lymphatic 

 Glands). 



[They are just small lymphatic accumulations around the arteries 

 periarterial masses of adenoid tissue similar to those masses that occur 

 in a slightly different form in other organs, e.g., the lungs. In a 

 section of the spleen the artery may pass through the centre of 

 the mass or through one side of it, and in some cases the tissue 

 is collected unequally on opposite sides of the vessel/ so that it is 



