Abstract
At the present time two methods for assaying progestin are in use, one involving the use of mature female rabbits, and the other, immature female rabbits. In connection with their work which showed that progestational proliferation is due to a specific corpus luteum hormone, Corner and Allen 1 developed a method for the standardization of corpus luteum extracts. The test devised consists of injecting the extract over a period of 5 days into a sexually mature doe castrated 18 hours after mating. A rabbit unit (Corner-Allen unit) is then defined as the minimum quantity of progestin which, divided into 5 equal daily doses, produces on the sixth day a state of the uterus equal to that of the eighth day of a normal pregnancy. A uterus in this state shows a +++ or ++++ proliferation.
Allen 2 discovered that, in the immature rabbit weighing from 575 to 1647 gm., progestational proliferation can be induced in the uterus by injections of progestin, provided the uterus is first influenced by a series of oestrin injections. Only a small percentage of the immature animals responded to the progestin treatment when it was not preceded by the oestrin injections. Clauberg 3 , 4 confirmed the findings of Allen 2 on immature rabbits and established the Clauberg unit which is measured in the same way as the Corner-Allen unit except that 600 gm. rabbits are used and are primed with a total of 80 international units of oestrin, administered in 8 daily injections of 10 international units each, preceding the 5 daily injections of progestin.
Get full access to this article
View all access options for this article.