ENDOCRINE ARITHMETIC 



2. How much progesterone is made daily in the ovaries of 

 one rabbit? Although the number of eggs shed by a rabbit at 

 one time, and hence the number of corpora lutea in one crop, 

 varies from 1 to 18, the number occurring most frequently 

 (modal number) is 8. Eight corpora lutea multiplied by 3.25 

 (the volume of one corpus luteum in cubic millimeters) and 

 then by 0.04 (the output of progesterone, in milligrams, by 

 one milligram of corpus luteum) gives the answer to question 

 2: The modal daily output of progesterone by the ovaries of 

 one rabbit is about 1.04 milligrams^ and the range is from 

 0.13 mg. when only one corpus luteum is present, to 2.3 mg. 

 with the maximum number of corpora lutea, namely 18. 



3. How much progesterone is produced daily by the ovaries 

 of a sow? This is important to know because the sow is the 

 source of most of the natural progesterone that has been 

 extracted and the only animal in which we know the amount 

 that is present in the ovaries at any one time. The volume of 

 one corpus luteum of the sow is approximately 625 cu. mm., 

 the equivalent of 160 rabbit corpora lutea. Assuming that 

 the corpora lutea of the two species are equally efficient, 

 volume for volume, and therefore that the amount of pro- 

 gesterone produced in each is directly proportional to the 

 amount of glandular tissue (an assumption for which at 

 present there is no evidence) then 1 corpus luteum of the 

 sow would produce 21 mg. of progesterone daily. 



In a sow possessing the modal number of corpora lutea, 

 which is 10 in that species, the total daily output of pro- 

 gesterone would be 210 mg. per day. The range would be from 

 21 mg. when one corpus luteum is present to 525 mg. with the 

 maximum recorded number of corpora lutea in the sow, 

 namely 25. This result seems improbably high, but since we 

 have no present means of improving it, let us use it tentatively 

 in answering the next question. 



4. How does the daily output compare with the amount 

 present in the ovaries at any one moment? All the corpora 



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