B L O OD-FOKMING GLANDS 



169 



stance as well as a sinus-like space that extends all over the periphery. 

 The afferent lymph vessels enter at one side of the nodule and the efferent 

 vessels pass out at the other (Fig. 150). 



A capsule of white connective tissue is formed around the whole 

 mass, and when the nodule attains a certain size, plate-like trabeculae 

 of this sheath are pushed into it to provide its soft tissues with mechani- 

 cal support. Elastic fibers and smooth muscle fibers may develop in 



per. s- 



med.a 



tr. 



L v. 



FIG. 150. Diagram of a lymph gland, aff.l.v., afferent lymph vessels ; eff.l.v., efferent lymph 

 vessels ; bl.v., blood vessels ; per.s., peripheral sinus ; l.s., lymph sinus ; no., lymph nod- 

 ule ; med.c., medullary cord ; tr., trabecula. (From "STOHR'S Histology" by LEWIS.) 



the connective tissue and trabeculae of the larger lymph glands. The 

 lymph sinuses usually touch the trabeculae and follow their course. 

 They thus come to lie between a trabecula and a mass of lymph tissue. 

 They are separated from the lymph tissue by a layer of flat cells which 

 may be considered to be the walls of the lymph sinus. 



The excavation of the lymph-cell mass (or lymph tissue) by the 

 lymphatics leaves it in a series of masses which when rounded are known 

 as the lymphatic nodules, and when elongate as the lymphatic cords. 

 The arteries and veins are found inside these masses. The lymph enters 

 such a gland and, in flowing through its sinuses, has added to its current 

 numerous lymph cells which creep out of the lymph mass, in which they 

 had their origin by cell division and development, and pass out of the 

 gland with the lymph. 



Bacteria and other harmful foreign bodies may be ingested by lymph 

 cells directly in the lymph glands. This process may go on until the usual 



