Abstract
Pelvic ligaments of guinea pigs undergo very pronounced relaxation during pregnancy to facilitate the birth of young. While studying the physiology of this reaction, one of us discovered that it was under hormonal control and that the substance responsible was present in the blood of certain mammals during pregnancy. 1 This hormone is capable of producing relaxation of the pelvic ligaments of virgin guinea pigs in a fashion typical of pregnancy, if given while the animals are in or recovering from oestrum. Later it was found that this reaction could also be produced through the use of extracts of corpora lutea of sows' ovaries. General methods for the preparation of these extracts have been given elsewhere. 2 These corpus luteum extracts, in addition to relaxing the pelvic ligaments, also produced other physiological changes ordinarily attributed to the corpus luteum, such as inhibition of ovulation, vacuolation of the vaginal mucosa of rats, 3 production of pseudo-pregnancy in rabbits, 4 and production of premenstrual endometrium in the uterus of castrate monkeys. 5
The opinion that more than one hormone was present in our corpus luteum extracts was expressed in some of our earlier papers. This has proven to be the case, since we have obtained a crystalline fraction which produces relaxation of the pelvic ligaments of the guinea pig, while the remaining fraction contains the active material which is responsible for the other physiological reactions. This paper deals with the preparation of the crystalline substance together with some of its properties.
The minced lutein tissue is extracted, for 48 hours, with twice its volume of acid alcohol, at room temperature. The alcohol is acidified by adding 2 cc. of concentrated HCl to 98 cc. of 95% alcohol.
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