i\llen: The Thyroid Gland and Hypophysis 



419 



larvae appear to show that the thyroid 

 gland and hypophysis act in a broad 

 general way upon growth and differen- 

 tiation of the soma rather than in 

 specific fashion upon certain parts. 

 Studies upon these growth procCvSses in 

 amphibians have an interest to us 

 because of their bearing upon human 

 problems; they furnish a basis for a 

 proper interpretation of important 

 pathological conditions in man. While 

 the study of clinical data has its im- 

 portant medical interest, we must 

 expect to find that the conditions 

 produced by disease of these glands 

 are much harder to analyze than are 

 the results reached by experimenta- 

 tion. 



ABNORMAL DEVELOPMENT OR GIGAN- 

 TISM 



We are familiar with the explana- 

 tions usually offered to account for 

 gigantism. Marie pointed out in 1886 

 that this condition of abnormal height 

 is usually the result of enlargement of 

 the hypophysis (pituitary gland) dur- 

 ing early life. Frequently this en- 

 largement is due to tumor formation 

 often the result of fracture of the skull 

 in the pituitary region. This early 

 increase in size at first leads to height- 

 ened function, but as the disease pro- 

 gresses it usually brings about an 

 under production of secretion leading 

 to lethargy and early death. This 

 disease of the pituitary gland produces 

 abnormal growth of the nose, lower 

 jaw and feet, and it causes the fingers 

 to assume a peculiar spatulate form and 

 to undergo a certain degree of pigmen- 

 tation. If this enlargement of the 

 pituitary gland takes place after the 

 attainment of maturity, the extreme 

 growth in height can not result because 

 the cartilage plates joining the ends of 

 the bones to the main central portion 

 have been ossified. This late develop- 

 ment of these symptoms without giant 

 growth is termed acromegaly. It has 

 been pretty well demonstrated that 

 these conditions result from abnormal 

 development of the anterior lobe of the 

 hypophysis (pituitary gland). And 

 the sharply defined experiments upon 



tadpoles as outlined above give very 

 definite support to this view. 



UNDER DEVELOPMENT — ^OR DWARFISM 



A certain type of dwarfism in which 

 the bodily proportions remain infantile 

 but where the mentality is normal or 

 nearly so, is termed ateliosis. Gushing 

 and others have attributed this condi- 

 tion to an under development of the 

 anterior lobe of the hypophysis. In 

 these cases the ends of the bones 

 remain separated from the main body 

 of the bone by plates of cartilage long 

 after the time when they should nor- 

 mally unite with it; but in spite of this 

 there is a peculiar inhibition of growth 

 and the bones all remain both short 

 and slender. We have not as clear 

 evidence that under development of 

 the anterior lobe of the hypophysis 

 produces dwarfism as we have regard- 

 ing the influence of its over develop- 

 ment in the production of gigantism. 



The thyroid gland is definitely in- 

 volved in another type of dwarfism 

 termed cretinism. These cases are 

 common in certain goitrous regions, 

 especially among the southern Alps, 

 and are often accompanied by that 

 disease. It frequently entails idiocy. 

 This condition results from thyroid 

 insufficiency during childhood, and is 

 the direct outcome of a failure of the 

 ossification process in the cartilage 

 plates near the ends of the bones. 

 The latter fail to grow in length but 

 may increase considerably in thickness. 

 While cretinism differs from ateliosis in 

 the fact that the body is more plump, 

 the mentality low and the skin coarse 

 and puffy and there is a general lower- 

 ing of metabolism, yet there is a 

 significant similarity between them in 

 the retardation of the process of ossi- 

 fication. This is in line with the work 

 of Mr. Terry done in this laboratory, in 

 which he showed that a similar inhibi- 

 tion of ossification is produced in tad- 

 poles as a result of removal of the 

 thyroid gland. These skeletal features 

 constitute merely a phase in the gen- 

 eral infantile conditions. In ateliosis 

 there is simply a failure to become 

 physically mature, probably due to 



