318 THE DUCTLESS GLANDS 



Q. The Relationships between the Thyroid Gland and 

 the Reproductive Functions 



In the case of women some kind of relationship between 

 the thyroid gland and the functions of reproduction has been 

 recognized for a very long time. Thus it has been known 

 that the gland is relatively larger in women than in men, and 

 the conspicuousness and relatively large size are more marked 

 after puberty and during the periods of menstruation and 

 pregnancy. We know from observations on cretins and upon 

 thyroidless animals that the proper growth and development 

 of the sexual organs depends on the functional integrity of 

 the thyroid gland. It is stated that sexual intercourse both 

 in men and in women entails increased activity of the gland 

 and gives rise to an increase in volume. McCarrison believes 

 that married men and women under forty years of age owe 

 their superior physique to the maintenance of thyroid activity 

 which marriage assures. 



The ovaries are believed to exert an inhibitory action on 

 the thyroid gland, so that the latter becomes over active after 

 castration. This hyperactivity is revealed by an increase in 

 the amount of colloid matter. This is also put forward in 

 explanation of the large number of cases of exophthalmic 

 goitre which occur after the menopause. Bearing in mind the 

 important though ill-understood relation between, the adrenal 

 cortex and the reproductive organs it seems probable that the 

 relations of the thyroid to the sexual functions will only be 

 fully understood when the functions of the adrenal are better 

 known. 



R. The Functions of the Thyroid Gland 



The evidence before us points to the conclusion that the 

 thyroid gland provides a substance or substances which aid 

 in the growth, morphological differentiation, and metabolic 

 processes of the body. One of these substances seems to be 

 an iodized amine thyroxin. Most of the activities attribut- 

 able to the active principle or principles are in the direction of 

 katabolism, though, according to some authorities, there are 

 indications of the existence of an anabolic principle. It is m.t. 

 known whether there are two separate active substances one 

 anabolic, the other katabolic. The secretion of the active 



