400 THE DUCTLESS GLANDS 



evidence is convincing. As we have already seen (p. 366), a 

 very striking effect is caused by removal of the thyroid upon 

 the pituitary body, which not only undergoes general enlarge- 

 ment, but exhibits well-marked indications of increased 

 secretion. 



There is, however, no increase in the amount of iodine in the 

 hypertrophied pituitar'es in these cases, so that a true vicari- 

 ous functioning seems out of the question. 



How far the parathyroids may be concerned in this question 

 we do not know. According to Halpenny and Thompson, 

 some of the alterations which have been described in the 

 pituitary occur when the parathyroids only are extirpated. 

 But other observers have failed to find any changes in the 

 pituitary after parathyroidectomy. 



When the pituitary hypertrophies as a result of sub- 

 thyroidism, there are no symptoms of superpituitarism. So 

 that the pituitary as a whole does not become more active. 



Relations between the Thyroid and the Reproductive Organs 



Many of the changes found in various organs of the body as 

 a result of thyroidectomy are not to be attributed directly to 

 a loss of the thyroid secretion, but to the effects of intoxication 

 and troubles of metabolism which supervene in these cases. 



In the female the thyroid is known to become enlarged at 

 puberty, at the menstrual periods, and during pregnancy. In 

 animals from whom the thyroids have been removed at an 

 early age, the reproductive organs are late in developing or 

 develop in an imperfect manner, so that we have a condition 

 of sexual infantilism. Some changes in the reproductive organs 

 have also been recorded in cases where thyroidectomy was 

 carried out in the adult. 



In exophthalmic goitre the sex functions are often affected 

 (menstrual disturbances) ; and there is sometimes atrophy of 

 the genital organs. In myxcedema there may be complete 

 impotence. The theory that the thyroids have a stimulating 

 effect on the reproductive organs has therefore some evidence 

 to support it. 



Some authors claim to be able to diagnose thyroid deficiency 

 in cases of incomplete sexual development and to remedy the 

 defect by thyroid medication. 





