CHAPTER III. 

 I. PATHOLOGY OF THE THYMUS. 



FUNCTIONS OF THE "THYMUS. 



The thymus in man consists of a cervical part, made up 

 of two diverging cones, which are attached to the thyroid 

 by fibrous tissue and are closely approximated to the 

 brachio cephalic and jugular venous trunks and a medias- 

 tinal part located between the chondro-sternal portion 

 of the thoracic cage in front, and the pericardium and the 

 large vessels at the base of the heart and the right ventricle 

 in the back. 



In the child, the thymus is a reddish gland, of soft con- 

 sistency, plastic, which moulds itself to the blood vessels, 

 insinuates itself between them and comes in contact with 

 the anterior surface of the trachea. It is not a definitely 

 demarcated organ: at a certain time of life it atrophies, 

 but does not, however, disappear completely. There is a 

 fatty change in the gland, but glandular lobules still persist 

 and in certain pathological conditions can regenerate. 



The time at which the thymus reaches its greatest 

 period of development and the time at which it begins to 

 atrophy is still unsettled. The French investigators give 

 as the weight of the thymus the following figures : at birth 

 3 to 5 grams (Hutinel and Tixier, Cruchet) ; at one year 

 from 5 to 8 grams (Marf an) ; between 3 and 4 years from 

 7 to 9 grams. According to some the regression begins 

 at the age of two, for others at four. 



Hammer, and then Sury, by studying the weight of the 

 thymus in individuals dying in accidents give very differ- 

 ent figures: at birth the thymus weighs 13 grams; from 

 1 to 5 years of age about 22 grams; from 6 to 10 years 



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