774 THE ENDOCRINE ORGANS, OR DUCTLESS GLANDS 



considerable number of years. The enlargement affects more particu- 

 larly the pars anterior, although changes are also described in the pars 

 intermedia et nervosa. Accompanying the enlargement of the anterior 

 lobe, vesicles containing colloid-like material often become developed in 

 it, but even after the hypertrophy has proceeded to a considerable de- 

 gree, this colloid does not contain iodine, nor does an extract have the 

 same physiological effect as one of the thyroid gland. It can not replace 

 thyroid extract in the treatment of patients with goiter or myxedema, 

 or ameliorate the symptoms produced in animals by the removal of the 

 thyroid gland. Deposition of colloid-like material in the pars anterior 

 also occurs in myxedema. Histological changes in the pars intermedia et 

 nervosa, although less pronounced than in the pars anterior, are never- 

 theless said to be perfectly distinct following thyroidectomy, and to con- 

 sist in an increase in the hyaline and granular masses which have already 

 been described as present to a certain extent in the normal gland. 



Less direct evidence of an association in function between the pituitary 

 and the thyroid is furnished by the similarity of the effects produced on 

 the sexual functions and on the general development of young animals 

 by the removal of either gland. In both cases the animals fail to grow 

 properly; the sexual organs remain undeveloped; and the mental func- 

 tions are infantile in type. In hypophysial deficiency, however, extreme 

 adiposity is likely to be more marked than is the case in cretinism. 



2. With the Sexual Organs. That the pituitary gland has much to do 

 with the development of the sexual organs has already been shown. Fur- 

 ther evidence of a relationship between the sexual glands and the pitui- 

 tary is furnished by the following observations. After castration en- 

 largement occurs in the pituitary, and on histological examination the 

 gland is found to contain a large number of oxyphile cells, particularly 

 in the pars anterior. This influence of the sexual glands on the pituitary 

 is believed to depend on the interstitial cells present in them, for it has 

 been found that if the ovary or testis is transplanted into other parts of 

 the body after the castration, the changes in the pituitary do not occur, 

 although, as we shall see, the transplanted gland becomes entirely 

 atrophied except for the interstitial cells. The enlargement of the pitui- 

 tary during pregnancy an enlargement which often brings it to two or 

 three times its normal weight is further evidence of its association 

 with the ovary. 



3. With the Suprarenals. Association of function is suggested in this 

 case by the fact that extracts of suprarenal and pituitary have very much 

 the same effects on involuntary muscular fiber and glandular structures, 

 and it is said that the two extracts mutually facilitate each other's 

 action in this regard. It should be remembered, however, that pituitrin 



