376 Development of the Lymphatic Nodes in the Pig 



The diagram shows the first beginning of the trabeculas in the con- 

 nective tissue that pushes down between the peripheral sinuses as these 

 surround the follicles (see dt on the figure). Neither the capsule nor 

 the trabecuhiB have fibers different from the surrounding connective tissue 

 at this stage. 



There are certain interesting points in regard to the cells of the node 

 at this stage. In the germ centers there is a marked division of the 



Fig. 13. Diagram ot the primary lymph node in an embryo pig, 15 cm. 



long. X about 33. The node shows several follicles. A, artery; aid, afferent 



lymph ducts; dt, developing trabecula; gc, germ center; ps, peripheral 

 sinus. 



lymphocytes. In any one section each center contains from two to 

 fifteen or more dividing lymphocytes. They are easily distinguished 

 from the dividing connective tissue nuclei, which are always larger and 

 have much more protoplasm. There are many eosinophiles in the 

 cords, but at this stage none are to be found in the germ centers. There 

 are numerous degenerating red blood cells. 



The next diagram (Fig. 14) is from the primary lymph node in a 

 pig 23 cm. long. Only a portion of the section was drawn, in order to 



