The principles of pathologic histology / by Frank B. Mallory.

  • Mallory, Frank Burr, 1862-1941.
Date:
[1914]
Catalogue details

Licence: In copyright

Credit: The principles of pathologic histology / by Frank B. Mallory. Source: Wellcome Collection.

    33/684 (page 33)
    reaction to simple necrosis where toxic substances derived from the necrotic cells act as an injurious agent, but in a seiitic infarct we have a double reaction, on the one hand to the necrotic cells, on the other to the toxic agent and to the toxins it generates. As a rule, in infectious processes the injurious agent causes a greater and more characteristic reaction than do the injured cells. It is not customary, however, or perhaps often essential, to separate the two kinds of reaction, but they should be liorne in mind. The reaction of the body to an infectious agent and its toxins, uncomplicated by any marked tissue injury, Ijeyond beginning general retrograde processes dependent partly on toxemia and partly on interference with nutrition, is best seen perhaps in sejiticemias, where the fight is directly between the irritant on the one hand and the blood plasma and the leukocytes on the other. Often the endothelial cells lining the blood-vessels play an important role also by incorporating many of the organisms, as in leprosy, tuberculosis, and dum-dum fever. We can get some idea of what is taking place by studying the variations in the relative proportions of the leukocytes, the chemical changes and altered serum reactions produced in the blood plasma and the clin- ical signs and symptoms. The fluitl and cellular elements in the blood- and lymjih-vessels at the service of the body in combating injurious agents and in aiding in the repair of injuries are few in number. Sometimes only one of them is used; more often two or more. AVe ordinarilj' express the condition of affairs in another way by saying that a certain irritant attracts or is chemotactic for a certain kind of leukocyte. The action exerted by the leukoc}ffes is to some extent, perhaps, mechanical, but their chief effect is produced chemically that is, is due to the action of chemical substances manufactured by the different leukocytes to neutralize the toxins secreted by micro- organisms and to dissolve necrotic cells. Some of these chemical substances can be demonstrated; others are recognized chiefly by the effects they produce. A certain number of them are present in the serum under normal conditions. The morphologic changes which take place as the result of the action of various injurious agents vary greatly, depending on the strength and character of the latter. Sometimes an irritant will produce one type of injury and reaction in one place (local action of the diphtheria toxin in the throat or of the diplococcus pneumoniaj toxin in the lung), and a different type of injury ancl action in another place where the toxin is carried in a dilute state (diffuse action of the diphtheria toxin in the lymph-nodules of the spleen, etc., or of the diplococcus i)neunionia3 toxin in the 3