no 



NORMAL HISTOLOGY. 



thus imperfectly defined by the trabeculae are incompletely filled by masses 

 of compact lymphoid tissue, the general form and arrangement of which 

 correspond to the compartments in which they lie. The masses contained 

 within the peripheral spaces are irregularly spherical or pyramidal and 

 constitute the cortical nodules ; those within the intercommunicating central 

 compartments form a network of irregular cylinders, the medullary cords, 

 which are continuous with one another and with the deeper part of the 

 cortical nodules (Fig. 148). 



The intervals between the tracts of lymphoid tissue and the trabecular 

 framework constitute a system of freely communicating channels, the lymph- 



Lym; 



Cortical follicle 



Lymph -si 



Lymph-sin 



Medullary 



V 



FIG. 149. Portion of periphery of lymph-node, showing relation between trabecula, sinus, and lymphoid 



tissue. X 50. 



sinuses, through which slowly passes the lymph brought to the node by 

 the afferent lymphatic -vessels. The latter pierce the capsule on the convex 

 surface of the node and open into the sinuses that partially surround the 

 cortical nodules. After traversing the peripheral sinuses, the lymph passes 

 into the irregular channels of the medulla and finally escapes from the node 

 through the efferent lymphatics, which usually emerge at the hilum, if one 

 be present, on the surface of the node opposite to the entrance of the afferent 

 vessels. The lymph-sinuses, therefore, are bounded on one side by the 

 capsule or trabeculse and on the other by the masses of dense lymphoid- 

 tissue. The lumen of these channels, however, is not free, but occupied by 

 a delicate wide-meshed reticulum consisting of fine strands of connective 

 tissue where most marked, or of the anastomosing processes of stellate cells 

 where very delicate. The sinuses are lined by an imperfect layer of flattened 

 plate-like ceiis, that represent the endothelium of the adjoining lymphatic 



