THE ENDOCRINAL ORGANS 



461 



thymus tissue to adenoid tissue makes it probable that it is a lymph- 

 forming organ, whatever other functions it may have. The most striking 

 histological characteristic of the thymus is the presence of thymic or 

 Hassall's corpuscles, relatively small clusters of concentrically arranged 

 epithelial cells, usually assumed to be degenerate and non-functional. 



Physiology. The endocrine function of the thymus is doubtful, 

 since removal of the gland is not followed by disturbances of normal 



Fig. 382. — A portion of a section of the thymus gland as seen under low power 

 microscope, showing its subdivision into lobules and their differentiation into cortical 

 and medullary portions. Thymic corpuscles which are peculiar to the thymus, occur in 

 the medullary regions. Two of these much enlarged are shown in the lower figure. 



functions. The enlargement of the gland in early life and its later 

 atrophy suggest that its functional activity may be limited to stages of 

 growth and differentiation. 



Hypertrophy of the thymus sometimes accompanies that of other 

 lymphatic organs, the condition being known as status thymicoljrmpha- 

 ticus. It results in serious metabolic disturbances and sometimes even 

 death. Adults in whom the thymus does not atrophy may die suddenly 

 under ether. 



