THE HORMONES IN HUMAN REPRODUCTION 



more or less like these examples and possess phenolic prop- 

 erties, as indicated by the OH group in at least one ring. 

 Until we know definitely just what the hormones do when 

 they reach the cells upon which they act, these facts will have 

 to suffice us. 



Potency of estrone. Estrone is a very powerful substance; 

 that is to say, only a very small amount is required to produce 

 large effects. It has to be used and talked about in quantities 

 too small for ordinary measures of weight, and so we mention 

 it in terms of the chemists' tiny unit, the gamma (y) which 

 is 1/1,000 of one milligram. An ordinary U.S. postage stamp, 

 gummed, weighs 60 milligrams ; one gamma is therefore 

 1/60,000 part of the weight of a stamp. As little estrone as 

 1/100 gamma, or 1/6,000,000 of a postage stamp, per day 

 for 3 or 4 days may be enough to produce estrous changes 

 in a castrated mouse, and even in a woman 20 gammas per day 

 (1/3,000 of a postage stamp) for 10 days may be sufficient 

 to produce certain profound effects upon the uterus which 

 we are going to consider in Chapter VI. Some of the other 

 estrogens are three or four times as potent as this. 



The total amount produced in one day by the two ovaries 

 of an adult woman is believed to be equal in potency to about 

 300 to 400 gammas of estrone, or something over 1/200 of 

 the weight of a postage stamp. 



By worldwide agreement through the League of Nations 

 an international unit of estrone was set up, for the benefit of 

 scientists and the drug industry. This is the amount of po- 

 tency in 0.1 gamma of the pure hormone. At first the League 

 of Nations Committee on Standardization of Drugs and Hor- 

 mones set aside in London a stock of the pure hormone to 

 serve in much the same way as the international standards of 

 weight and length (metric system) in Paris. Any responsible 

 person who wished to test his own product could get a few 

 units from London and compare the effectiveness of the two 

 samples in rats or mice. It is good to know that if the precious 



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