134 



rui-: ORGANS. 



oid tissue continuous with the round masses outside. The gland 

 is thus divided into two zones, a cortex and a medulla. 



The cortex is divided by the trabeculse into follicles, while 

 the medulla consists of much smaller masses of adenoid tissue, 

 known as medullary cords (Fig. 94). These are directly con- 

 tinuous with one another. 



The reticular connective tissue which fills the spaces between 

 the trabeculae contains very few lymphocytes in the immediate 

 neighborhood of the trabeculse and the capsule. Farther away 

 from these, however, the lymphocytes are very numerous and 



FIG. 94. 



Capsule 

 Medullary cord* 



:L. vy : y , 



Follicle* Hilns wii 



ententig Medullary substance 



Section through a small lymph gland of a dog. v 20. 



make up the follicles and lymph cords. These latter masses 

 are therefore surrounded by almost empty spaces which separate 

 them from the trabeculse and capsule. These spaces are called 

 lymph sinuses (Fig. 96). They contain a fine reticulum, which 

 passes over the trabecula3 on one side and the follicle on the 

 other. The lymph sinus is a continuation of the lymph-vessels, 

 and, like these, is lined with flat endothelial cells whose presence 

 can be demonstrated by silver nitrate. This endothelium prob- 

 ably does not form a continuous membrane. The cells are 

 often found separated and lying freely in the lymph sinus. 



