IDENTIFICATION OF ESTRADIOL - 17 j 3 FROM DOGFISH OVA (

Although estrogenic activity of ovarian extracts has been reported for all classes of vertebrates and certain invertebrates, the chemical nature of the active compounds has been identified only in mammals. The hormone of the graafian follicle was isolated by MacCorquodale, Thayer, and Doisy (1) from liquor folliculi of sow ovaries and named dihydrotheelin, a synonym of estradiol-17p according to present nomenclature. When whole ovaries were extracted, both estradiol-17p and estrone (theelin) were obtained (2) in an approximate ratio of 0.014:0.010 mg. per kilo. It seems probable, as suggested by these authors and later by others, that estradiol17/3 is the estrogenic hormone secreted by the graafian follicle and that estrone is a metabolite. While this may be true for mammals, such information is lacking for other vertebrates. In the present investigation an attempt was made to identify the estrogenic hormone in the mature ova of the dogfish, Squalus suckleyi.