XIV 



THE LYMPH 



531 



network which divides the medulla into a number of spaces, much 

 smaller than the alveoli, that communicate freely among themselves 

 to form a labyrinth. The capsule and cortical trabeculae and the 

 network of medullary septa make up the skeleton or supporting 

 tissue of the lymphatic gland (see Fig. 249). 



Each alveolus of the cortex is occupied by adenoid tissue rich 

 in leucocytes, in structure very similar to a solitary follicle, and 

 therefore known as an alveolar follicle. This is separated from 

 the walls of the alveoli (represented by the capsule and trabeculae) 

 by a lymph sinus, which 

 merely differs from that 

 surrounding a solitary fol- 

 licle by the fact that its 

 lumen is traversed by a 

 larger amount of reticu- 

 lated tissue (Fig. 250). The 

 medullary spaces, too, are 

 occupied by follicular sub- 

 stance in the form of rami- 

 fied and anastomosing cords 

 known -as the medullary 

 cords. These also are sur- 

 rounded by lymph sinuses 

 throughout their course. 

 As the adenoid tissue of the 

 cortical follicles continues 

 in the medulla as the med- 

 ullary cords, so the circuin- Fl( 

 follicular lymph sinuses 

 continue in the spaces 

 which surround the medul- 

 lary cords. In the hiluni 

 of the gland the whole of 

 the lymph sinuses collect 

 into a terminal sinus, which 



communicates with the efferent lymphatics. The afferent lymph- 

 atics, after forming a plexus between the two layers of the capsule, 

 communicate with the perifollicular lymph sinuses. Like the 

 lymph sinuses of the solitary follicle, those of the glands are 

 invested with epithelioid platelets as shown by the silver nitrate 

 reaction. 



The small arteries which penetrate into the hiluni of the gland 

 ramify along the trabecular skeleton, here and there giving off 

 branches that traverse the sinuses and plunge into the adenoid 

 tissue, where they are resolved into a capillary network that 

 extends to the medullary cords and the follicles contained in the 

 alveoli. The small veins that arise from the capillary rete also 



J. 250. Cortical section of lymphatic gland of man. 

 through capsule, cortical sinus, and peripheral portion 

 of a follicle. Many of the lymphocytes have been 

 removed by the shaking. (Klein.) c, Capsule com- 

 posed of external fibrous stratum, and internal layer 

 of flat, nucleated corpuscles of connective tissue ; 

 x, circumfollicular lymph sinus, containing largo 

 meshed reticulum of ramilied connective-tissue cells ; 

 a, adenoid tissue of a follicle, composed of network 

 with finer and more compact meshes. Magnification, 

 350 diameters. 



