HORMONES 



been studied first clinically and afterward experimentally, e. g., Addi- 

 son's disease, acromegaly, etc. 



Quantitative Determination of Hormones. The hormone or 

 its derivatives can be determined in the organ, blood, or urine. The 

 determination can be made by chemical, physical, or biological 

 methods. The low concentration of the hormone rarely allows direct 

 gravimetric estimations; in general, these must be based on colori- 

 metric, spectrophotometric, or chromatographic methods. Biological 

 assays are performed on entire animals, isolated organs, or tissue slices. 

 Animals with insufficiency may be used. In some cases the organ is 

 forced to function overloaded, e. g., a pancreas grafted in diabetic 

 dogs by vascular grafting is tested for the time necessary to correct 

 hyperglycemia. 



Hormones are assayed by comparing their effects with those 

 produced by international standards, thus avoiding differences of 

 sensitivity encountered in different races of animals. In order to 

 confirm that a given function depends on an endocrine organ, the 

 following consequences must be etablished: (7) the ablation or injury 

 of the gland must produce an insufficiency of that function; (2) this 

 deficiency must be compensated for by the graft or implantation of the 

 gland, or by the injection of its extract or its hormone; (3) an excess 

 of these substances must induce hyperfunction symptoms opposed to 

 those of hypofunction; (4) the anatomoclinical facts must agree with 

 the experimental findings; (5) both spontaneous and induced hyper- 

 function must be improved by treatments which either eliminate the 

 gland or decrease its action. 



In order to admit that a given action due to an endocrine gland 

 is produced through the mediation of another gland, it is necessary to 

 show: (7) that the removal of the second gland is followed by a condi- 

 tion of hypofunction, just as, or even more, pronounced than that 

 caused by the ablation of the first; (2) that the disturbances cannot 

 be corrected either by implantation or injection of extracts or hormones 

 of the first gland when the second one has been removed. For example, 

 (a) ovariectomy leads to atrophy of the uterine and vaginal epithelium, 

 just as much or more so than hypophysectomy, and (b) the pituitary 

 gonadotropins produce hyperplasia of the uterine and vaginal epi- 

 thelium only when the ovary is present. These facts lead to the 

 conclusion that the effect of the hypophysis on the uterine and vaginal 



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