THE LYMPH-NODES. 



109 



Trabeculae 



and the typical lymph-nodes on the other, stand such structures as Peyer's 

 patches and the faucial tonsils, in which groups of simple nodules are blended 

 into a single organ, the component nodules only partially retaining their 

 individuality. 



The lymph-nodes are flattened oval or bean-shaped bodies, from a few 

 millimeters to two centimeters or over in length, that are scattered along the 

 lymphatic vessels, some- 

 times singly but often in 

 chains or groups. On 

 nearing a node, the lymph- 

 vessel divides into a num- 

 ber of stems, the afferent 

 vessels, which enter the 

 substance of the node and 

 communicate with the cap- 

 illary network within its 

 interior. From the latter 

 other channels, the efferent 

 vessels, arise and emerge 

 from the node at a point 

 usually, but not always, 

 marked by a slight de- 

 pression, the hilum. The 

 lymph-nodes are invested 

 by a distinct fibrous capsule, 



Lymph- 

 sinus 



Capsule 



FIG. 147. Diagram illustrating architecture of lymph-node. 



in which elastic fibres and occasional unstriped muscle are present. From 

 the inner surface of this envelope, the fibre-elastic tissue is continued into 

 the substance of the node in the form of numerous radially directed trabeculae, 



Germ- 

 Lymph-sinus centre 



Fat 



apsule 

 Trabecula 



ical follicles 



Lymph-sinus 



Hilum Efferent lymphatics Medullary cords 



FIG. 148. Section of small lymph-node through hilum. X 23. 



which thus subdivide the outer zone, or cortex, into a series of compartments. 

 On reaching the inner limit of the cortical zone, the trabeculae are less 

 regular and freely anastomose, thereby breaking up the deeper parts of the 

 node, the medulla, into uncertain cylindrical compartments. The spaces 



