Abstract
In a previous paper, Macht, Stickels and Seckinger described their experiments with injections of corpus luteum extracts on the oestrus cycle of guinea pigs, as studied by the vaginal smear method. 1 It was pointed out that injections of such extracts produced an inhibition of the oestrus and were accompanied by characteristic histological findings. Inasmuch as a great deal of the earlier work with ovarian endocrines was done by feeding glandular substance to animals and human beings, it seemed desirable to inquire as to whether or not such feeding experiments in the laboratory would be followed by results similar to those obtained with injections. In the present paper a report is made of the results obtained in a series of feeding experiments on guinea pigs performed in this laboratory for a period of about one year.
The method of experimentation was as follows: A series of guinea pigs was carefully studied to establish the duration of their normal oestrus cycle. This was done by microscopic examination of vaginal smears made daily over long periods of time. After determining the length of the oestrus cycle in each case, the guinea pigs were daily fed from 0.1 to 0.2 gm. of desiccated corpus luteum substance suspended in fresh cow's milk. Such a suspension can be easily administered to a guinea pig by means of a glass dropper or pipette. The corpus luteum substance used was obtained from the sow. Fresh glands were dried in vacuo under slightly diminished pressure at a temperature of from 80° to 85° Fahrenheit. The desiccated gland was then powdered and used, the powdered gland being equivalent by weight to about 20 per cent of the fresh gland.
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