LYMPHATIC NODES OB GLANDS 113 



Lymphoid or adenoid tissue consists of a mass of flattened cells, 

 with numerous delicate fibrillar prolongations, which branch and 

 anastomose so as to form an interwoven structure the adenoid 

 reticulum. Klein regards the cells as forming no essential part of- 

 the structure, but considers them as flattened plates attached to the 

 fibrils. The meshes of the adenoid reticulum are in connection 

 with the fibers of the trabeculae, and, with the exception of the 

 portion next the latter, are filled crowded, in fact with countless 

 small, spherical lymphoid cells. Those portions of the tissue which 

 contain the cells are termed the follicles of the cortex and cords of 

 the medulla. 



The lymph -path is the portion between the fibrous trabeculae 

 and the follicles and cords. 



When we learn that the trabeculae, follicles, cords, and lymph- 

 paths pursue very tortuous and branching routes, we can appreciate 

 the complexity of the organ as a whole. 



The blood-vessel arrangement presents no anomalies. The 

 small arterial trunks enter within the trabeculae, finally break into 

 capillaries which supply the follicles, cords, etc., and the blood is 

 then collected by the venules for the efferent veins. 



There is a depression at one side of the lymph -node called the 

 hilum, where the arteries enter, and the veins and efferent lym- 

 phatic leave the lymph -node. 



Small diffuse collections of adenoid tissue are to be seen in many 

 organs. These do not differ essentially from the tissue just 

 described, excepting that there is no definite arrangement of 

 trabeculae and lymph -paths, as in the compound lymph -node; the 

 lymph simply filters through the reticulum, the same being a part of 

 the lymph -channel system of the tissue in which the adenoid struc- 

 ture may occur. 



PRACTICAL DEMONSTRATION 



The mesenteric lymphatic nodes present the most typical structure, and may 

 be obtained from the human subject, if fresh, although those from the dog are 

 preferable, on account of the better condition of the tissue as usually secured. 



The nodes should be sliced in half, placed in Miiller for a week, and then 

 hardened by two days immersion in strong alcohol. 



Sections should be mounted, of two kinds, viz., those including the whole 

 area of the node which need not be very thin for demonstration of the 

 scheme or plan of structure, and exceedingly thin ones, even though they may 

 include only a small part of the organ, for study of the details of the adenoid 

 reticulum. The latter purpose will be subserved by shaking a number of thin 



