Physiology and Experimental 

 Pathology of the Thymus Gland 



B. G. HOSKINS 



COLUMBUS 



The researches of recent years have more and more tended toward a 

 conclusion that the chymus gland has no true internal secretion. In view 

 of the fact, however, that this structure is widely regarded as an endocrin 

 organ, a brief discussion of the evidence seems incumbent. 



Studies on the functional significance of the thymus have been directed 

 chiefly to observations upon the effects of extirpating the organ and of 

 injecting extracts of it into experimental animals. Such studies have 

 been supplemented by feeding experiments and by investigations of the 

 morphological conditions in the gland under various conditions. 



Effects of Thymus Extirpation 



A great many studies upon the effects of thymus extirpation are now 

 to be found in the literature. Apparently, the first investigator to concern 

 himself with the problem was Restelli in 1845. He attempted to remove 

 the gland from 98 animals sheep, dogs, and calves. Of these, 4 sheep, 

 1 calf, and 1 dog only survived. All of the animals seem to have been 

 infected, and no significant data resulted from the study (Park and 

 McClure). 



Friedleben (1858) published a monograph of 336- pages on the 

 thymus gland. He removed the organ from 3 goats and 15 dogs. The 

 extirpation in the goats was incomplete. In 7 of the dogs it was thought 

 to be complete, and in 5 was known to be only partial. In 3 cases the 

 spleen, as well as the thymus, was removed. The age of the dogs at the 

 time of operation varied from 6 days to 4 months. The results in the 

 goats may be disregarded. Friedleben concluded that the thymus is not 

 essential to life, but that the loss of the spleen and thymus together is 

 necessarily fatal, on account of the resulting disturbances of blood forma- 

 tion. The thymus itself he regarded as having an important function 

 relating especially to blood formation, nutrition and growth. The chief 



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