104 THE CIRCULATORY SYSTEM. 
is believed to be incited by the entrance of some septic material from 
an injury or wound of adjacent structures. In mild cases there may 
be no microscopical changes that are apparent, but in the severe cases 
the wall of the affected vessel is infiltrated with pus, and its lumen 
may contain pus, fibrin, and desquamated endothelium. The presence 
of tubercle bacilli may produce a tubercular lymphangitis. The vessel 
may also be the seat of gummata due to the poison of syphilis. 
What forms of inflammation are common to lymph nodes ? 
Acute, chronic, tubercular and syphilitic inflammations. 
What are the changes in acute inflammation ? 
This form of inflammation is usually secondary to inflammatory 
change in the vicinity of the affected node. There is a marked 
increase of cells in all parts of the node. In the follicles and cords 
these cells are small and round resembling those normally present. In 
the lymph sinuses are large polyhedral cells with large nuclei. The 
endothelial cells lying on the reticular structure of the node are swol- 
len. The bloodvessels may be swollen and blood may be free in the 
lymph sinuses or in the follicles. This form of inflammation may 
terminate in resolution, the new cells undergoing fatty degeneration 
and being absorbed. Or the inflammation may become purulent and 
so extensive that abscesses are formed. Lastly, acute inflammation 
sometimes passes into the chronic form. 
What changes are seen in chronic inflammation of lymph nodes ? 
There is simply an increased growth of connective tissue in the cap- 
sule, and trabeculee and the reticular structure of the node becomes 
thickened and fibrous. As the amount of connective tissue increases 
there is a corresponding decrease in the number of lymphoid cells. 
The process may go on until the whole node is converted into a mass 
of connective tissue. 
Describe tubercular inflammation of lymph nodes. 
It may occur with simple inflammation, or be secondary to tubercular 
infection in other parts of the body. 
The microscopical changes are the same as in tubercular inflamma- 
tion elsewhere. These may be all. But often are noted in addition 
the following changes: The node is swollen and feels harder than normal. 
On section the cut surface is of a reddish gray color. The parenchyma 
cells, on microscopical examination, are found to be increased in num- 
ber, some being small and spheroidal, others large and polyhedral, 
Some of the cells become filled with a highly refractile material, and 
