THE THYROID 



The accessible position of the thyroid gland has 

 enabled clinicians to pay some attention to the obvious 

 connexion of this organ with the genital functions. 



At puberty a temporary enlargement — especially 

 during menstruation — may often be observed in women ; 

 and in all mammals we invariably find the thyroid 

 considerably increased in size during pregnancy. 



This temporary enlargement indicates, of course, a 

 change in the secretory activity of this organ to meet 

 the metabolic requirements in these circumstances. 



We shall, perhaps, be in a better position to appreciate 

 the changes that occur in the rest of the genital system 

 if we first consider the effects on the general metabolism 

 of removal of this organ. 



Effects of 

 thyroidec- 

 tomy vary 

 in different 

 animals. 



EFFECTS OF THYROIDECTOMY ON THE GENERAL 

 METABOLISM 



Different mammals vary very much in their power 

 of withstanding the disastrous results which may follow 

 complete removal. Grave effects never supervene on 

 the removal of the thyroid in rabbits ; and this ex- 

 emption has been explained, as we have already seen, 

 on the ground that the parathyroids are relatively large, 

 and lie well away from the thyroid itself, and conse- 

 quently cannot be removed without a careful search — in 

 other words, they escape removal during the operation 

 of thyroidectomy. Swale Vincent and Jolly 1 have 

 shown that after thyroidectomy the parathyroids 

 actually secrete colloid, and, in fact, after this operation 



1 Vinoent, S., and W. A. Jolly, Journ. Physiol, 1904-5, vol. xxxii, 

 p. 65. 



