A HORMONE FOR GESTATION 



mone became known, the chemists, led by the amiable and 

 diplomatic Butenandt, suggested the suffix -sterone. This 

 tells us that the substance is a sterol containing doubly-linked 

 oxygen. 



Progesterone it is, then; and my original name progestin 

 is retained for use as a general term when we need to talk 

 about such a hormone without specifying its exact chemical 

 structure. As a matter of fact, some of the other sterols have 

 been found to produce progestational proliferation, though 

 rather feebly in comparison with progesterone itself, and as 

 a group we can call these "progestins," just as we use estro- 

 gen as a general term and specify estrone, estradiol, etc. as 

 individual substances. 



Natural sources of progesterone. The corpus luteum is the 

 only important natural source of progesterone. It has been 

 extracted not only from the sow, but also from the whale, 

 whose 2-pound corpus luteum contains a large amount. A 

 progestin (probably progesterone) has been extracted from 

 the cow. There is a little in the human placenta, and most 

 curiously of all, the adrenal gland contains something that 

 gives similar effects in animals. 



Potency of progesterone; administration. This hormone is 

 not as potent, weight for weight, as the estrogens. Direct com- 

 parisons are scarcely possible, for the two kinds of substances 

 do different things ; but if we compare the amounts necessary 

 to produce definite effects in the whole uterus and whole 

 vagina of an animal respectively, we have to use doses of 

 progesterone several hundred times larger than of estrogen. 

 Like coal and dynamite, they exert their power in different 

 ways. 



In 1935 the League of Nations Commission on Biological 

 Standardization agreed upon an international unit of pro- 

 gesterone, namely the amount of potency in 1 milligram of the 

 chemically pure hormone. This is 1/60 of the weight of a 



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