. Swine practice . Swine. 334 SWINE PRACTICE Lesions.—The typical initial lesion of tuberculosis is the tubercle which has been aptly defined as a nonvascular nodule composed of leukocytes, endothelial, giant and connective tissue cells, with a ten- dency for the central part of the nodule to undergo necrosis. There may be a slight variation in the tubercle in different animals, due to variation of susceptibility of the animal and variation of the virulence of the infecting bacilli. The typical lesion may also be materially modified by secondary lesions. Tuberculous lesions may occur in any ti
. Swine practice . Swine. 334 SWINE PRACTICE Lesions.—The typical initial lesion of tuberculosis is the tubercle which has been aptly defined as a nonvascular nodule composed of leukocytes, endothelial, giant and connective tissue cells, with a ten- dency for the central part of the nodule to undergo necrosis. There may be a slight variation in the tubercle in different animals, due to variation of susceptibility of the animal and variation of the virulence of the infecting bacilli. The typical lesion may also be materially modified by secondary lesions. Tuberculous lesions may occur in any tissue or organ, but lymphoid tissue is most frequently affected. The tubercle bacilli and their products are the causative factors in the formation of a tubercle. Having lodged in a tissue favorable for their growth and development, the bacilli begin to multiply and to eliminate products that stimulate the surrounding connective tissue and endothelial cells to increase in number, and at the same time exert a positive chemotactic action upon the leukocytes. In swine there is a very marked chemotactic action and limited stimulation of. Pig. 98. TUBERCiTLosis OF THE A, the skin showing caseo-calcareous lesions; B. subcutaneous fat. C, muscle. connective tissue. The typical porcine tuberculosis tubercle is largely composed of leukocytes and has little fibrous tissue. Tubercles grow because of the increased accumulation of leukocytes and the formation of a small quantity of fibrous tissue. The tubercle contains no blood vessels; that is, it is nonvascular, although in the early stages there may be a hypermic zone around the tubercle. This liyperomic zone is the result of irritation in the tissue, the tubercle formation causing a tissue reaction. As the tubercle becomes larger, due to the accumulation of leukocytes on the margin, the central part begins to degenerate. Porcine tubercular lesions are characterized by enlargement of. Please note that these images are extracted f
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectswine, bookyear1921
