LYMPH NODULES 



233 



are clothed by a single layer of pavement cells which is said to be in- 

 complete in places. This epithelium (mesenchymal epithelium) ~is sup- 

 ported upon a layer of 

 firm fibrous tissue 

 richly supplied with 

 both lymph and blood 

 capillaries. In the re- 

 cesses of the joints the 

 synovial membranes 

 are frequently thrown 

 into small villous 

 folds, which are chief- 

 ly formed by the inner 

 portion of the fibrous 

 coat and are covered 

 with epithelium; 

 these are the synovial 



The bur see and the 

 synovial sheaths of the 

 tendons are of similar 

 structure. 



Both the serous 

 and the synovial mem- 

 branes are moistened by fluid which contains leukocytes in small num- 

 bers, and closely resembles the lymph and tissue juice in its composition. 



FIG. 240. SECTION OF A VASCULAR SYNOVIAL VILLUS 

 FROM THE KNEE JOINT OF A CHILD. 



Hematein and eosin. Photo. X 200. 



LYMPH NODULES 



(Lymph Follicles) 



The lymph nodule is a structural unit of lymphoid tissue which may 

 exist independently, as in the solitary nodules of the intestinal tract, or 

 may form groups or accumulations consisting of a greater or less number 

 of nodular units. In this latter condition they occur in the mucous 

 membrane of the small intestine as Peyer's patches, in the tongue as the 

 lingual tonsil, in the fauces as the faucial tonsils, in the pharynx as the 

 pharyngeal tonsil, in the wall of the laryngeal cavity, in the spleen as 

 the Malpighian (splenic) corpuscles, in the lymph nodes as the peripheral 



