8i4 



A MANUAL OF ANATOMY 



Capsule 



Trabecula 



plain muscular tissue, all of which build up a strong distensible 

 tunic. 



The organ is composed of a trabecular network, the spleen pulp, 

 bloodvessels, and Malpighian corpuscles. 



The tunica propria sends into the organ a number of trabeculae 

 which, like the tunica propria, are composed of fibrous, elastic, 

 and plain muscular tissues. 

 These divide and subdivide, 

 and unite with one another, 

 as well as with processes de- 

 rived from the sheaths which 

 the bloodvessels carry in with 

 them at the hilum. There is 

 thus formed a trabecular 

 network which pervades the 

 interior, and contains in its 

 meshes the spleen pulp, capil- 

 lary tufts, and Malpighian 

 corpuscles. 



The spleen pulp occupies 

 the meshes of the network 

 formed by the trabeculge. It 

 is soft, and has a dark red 

 colour, which, however, be- 

 comes brighter on exposure 

 to the air. The matrix of the 

 spleen pulp is reticular, and 

 is formed by branched con- 

 nective-tissue corpuscles, 

 which constitute the susten- 

 tacular cells of the organ. 

 The matrix is, therefore, in 

 reality retiform tissue. The interstices of the reticulum contain 

 blood, in which there is a large number of white corpuscles, and 

 also special cells characteristic of the spleen, and called the splenic 

 cells. These latter are of large size, and are amoeboid. They 

 contain pigment, and red blood-corpuscles in various stages of 

 disintegration. 



Bloodvessels and Malpighian Corpuscles— Arteries.— The splenic 

 artery furnishes five or six large branches which enter the organ 

 at the hilum, and carry in with them trabecular sheaths from the 

 tunica propria. In the interior they divide and subdivide, and 

 finally terminate in pencil-like clusters of capillary vessels, by which 

 time they have laid aside all their coats except the endothelial 

 lining. The endothelial cells then become separated from each 

 other by spaces, and, being continuous with the sustentacular cells 

 of the spleen pulp, the blood flows directly into the interstices of 

 the reticulum of the pulp. The arteries, which are at first accom- 

 panied by trabecular sheaths, ultimately lose these sheaths, and 



Malpighian 

 Corpuscle 



Spleen Pulp 



Fig. 351. — Section of the Spleen. 



