THE HORMONES IN HUMAN REPRODUCTION 



tions, the dail}' dose can be brought down to about 0.13 mg. 

 Let us take this lower figure as the basis for subsequent calcu- 

 lations. It may help to visualize the quantities we are dis- 

 cussing if we remind ourselves again that an ordinary postage 

 stamp weighs 60 milligrams. 



From (a) and (b) we may conclude that one corpus luteum 

 produces about 0.13 mg. of progesterone daily. Here we are 

 making another assumption, namely that the progesterone 

 we administer in oily solution is utilized by the rabbit as 

 efficiently as she can utilize the progesterone she makes in her 

 own ovaries. This is really not impossible, for only very small 

 amounts of oil are used and they are slowly but completely 

 absorbed. This point will be discussed again later when we 

 attempt to calculate the rate of output of estrogenic hor- 

 mone. 



Our calculation can be checked roughly by considering 

 another action of progesterone, namely the maintenance of 

 pregnancy in the rabbit. This requires more of the hormone. 

 Brouha found that to preserve pregnancy to the 8th day, the 

 rabbit must have three or more corpora lutea (instead of 

 merely the one corpus luteum required to produce typical 

 changes in the uterus). If we want to maintain pregnancy 

 with progesterone after removal of the ovaries, we must also 

 increase the dose something like 3 times or more. Willard 

 Allen found 0.5 to 1.0 mg. of progesterone daily to be the 

 necessary dose. In this sort of experiment we find therefore 

 that one corpus luteum provides the equivalent of 0.16 to 0.33 

 mg. of progesterone daily, a figure in crude agreement, at 

 least, with that of 0.13 mg. arrived at previously. 



The volume of tissue in a rabbit's corpus luteum is approxi- 

 mately 3.25 cubic millimeters. Dividing this into the daily 

 output of 0.13 mg., we get the answer to question 1: One 

 milligram of rahhifs corpus luteum produces about O.O4 

 milligram of progesterone daily, 



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