450 



THE CIRCULATORY SYSTEM. 



INFLAMMATION. 



FIG. 246.-CHROMC ARTERITIS -A RTKRIO- 

 SCLEROSIS OBLITERATING ENDARTERITIS. 



Showing a thickening of the intima in 

 small artery of the brain. 



Acute Arteritis. Acute inflammation of the walls of the arteries is, in 



the majority of cases, the result of injury, or of an inflammation in the 



vicinity of the vessel, or of the lodg- 



^.^1:-^^:, ment within it of some foreign body of 



-> /. ' , . r .- \ an irritating or infectious nature. The 



; :--'^x ; ''' /^^^^ inflammatory process may be largely 

 confined to the inner coat of the ves- 

 sels endarteritis ; or it may commence 

 in the outer coats periarteritis ; or it 

 may involve the entire wall. 



The blood-vessels in the outer coats 

 may be congested, the tissue oadema- 

 tous and infiltrated with pus cells, and 

 the entire wall may become necrotic. 

 The iutima, if this layer be involved, 

 loses its natural gloss and looks dull 

 and is swollen. Under these conditions 

 thrombi usually form, and in these may 

 occur the various changes which have 

 been already described on page 73. 

 Chronic Arteritis (Arterio-Sclerosis) . Since the publication of the 



studies of Gull and Button on arterio-capillary fibrosis, attention has been 



every year more and more directed 



to chronic pathological changes in 



the arteries as of great frequency 



and importance. These changes 



are productive and degenerative in 



character and have an important 



bearing upon the circulation and 



upon the integrity of the vessel 



walls. They are in part primary, 



in part secondary, and may involve 



single vessels or vascular territories 



or may affect the entire vascular 



system. 



The lesions differ somewhat in 



the small and large vessels. In 



very small arteries there is a more 



or less general though not uniform 



thickening of the iutima (Figs. 246 



and 247). This is due in part to a 



proliferation of the eudothelium, in part to increase in the connective 



tissue of the intermediary layer. In this way a considerable amount of 



moderately cellular fibrous tissue (Fig. 248) may form within the mem- 





FIG. 247. -CHRONIC ARTERITIS ARTERIO-SCLE- 

 ROSIS OBLITERATING ENDARTERITIS. 



The new-formed tissue is most abundant at one 

 side of the vessel, where the external coats are 

 pouched. There is degeneration of the new-formed 



