LVMPHOID TISSUE, LYMPH -NODULES, AND LYMPH-GLANDS. 199 



minated follicles above mentioned. They form a peripheral layer 

 which is, however, not clearly defined in the neighborhood of the 

 hilum. This layer is known as the cortex of the lymph-gland. 

 (Fig. 1 6 1.) The lymphoid tissue of the interior of the gland, the 

 medullary substance, is in the shape of cords medullary cords 

 which are continuous with the lymphoid nodules of the cortical 

 portion. These connect with each other and form a network of 

 lymphoid tissue, in the open spaces of which lie the trabeculae. At 

 their periphery the nodules and medullary cords are bordered by a 

 wide-meshed lymphatic tissue, the lymph-sinus of the -gland, parts 

 of which lie (i) between the capsule and the cortical substance, (2) 



Germ center. 



Mitosis. 



Lymph-sinus. 



Fig. 162. From a human lymph-gland ; X 2 4 At a are seen the concentrically 

 arranged cells of the lymph-nodules. (Fixation with Flemming's fluid.) 



between the nodules of the latter and the trabeculae, (3) between 

 the medullary cords and the trabeculae, and (4) between the medul- 

 lary substance and the capsule at the hilum. At the hilum the 

 loose lymphoid tissue represents a terminal sinus (Toldt). These 

 sinuses are lined throughout by endothelial cells, which are continu- 

 ous with those of the afferent and efferent lymph-vessels. The 

 lymph flows into the gland through the afferent vessels, and passes 

 along into the interior through the spaces offering the least resist- 

 ance (sinuses). The latter represent those peripheral portions of 

 the nodules and of the medullary cords in which the lymphoid tissue 

 is present in loose arrangement. The lymph consequently envelops 



