274 DAVID MAKINE 



^ Atrophy 



Normal > Hypertrophy > Hyperplasia 



\v 



Involution 



i 



Colloid gland (goiter) 



^_ v Atrophy 



Colloid >- Hypertrophy >- Hyperplasia 



\ 



Involution 



{ 



Colloid 



Colloid >- Hypertrophy 



Whenever the iodin store of the normal thyroid falls below the normal 

 minimum (0.1 per cent) the gland undergoes changes characterized by a 

 general increase in its blood supply, a general decrease in the stainable col- 

 loid, and a general change from cuboidal to columnar epithelium. If these 

 changes continue to the stage of cell proliferation it is properly designated 

 as hyper pi asia. There are all degrees* of cell growth from the slightest 

 departure from normal (hypertrophy) to the most marked proliferations 

 (hyperplasia). The great majority of all glands showing hypertrophy and 

 hyperplasia never proceed to the stage of clinical detectability as indicated 

 by visible enlargement or by any symptom complex. Clinically, therefore, 

 goiter must be considered relatively rare, while histologically it is ex- 

 tremely common. 11 yperplasias may be classified as follows: 



1. Primary, that is, developing on a normal gland basis. 

 Developmental stage (compensatory). 

 Involutionary stage (physiological recovery). 

 Atrophic stage (physiological exhaustion). 



2. Secondary, that is, developing on a colloid gland basis. 

 1 )evelopmental stage. 



Involutionary stage. 

 Atrophic stage. 



