Although several investigators1 contributed to the early development of research on estrogens, rapid progress did not begin until after the publication of the vaginal smear reaction2 for the detection of these substances. The work was given additional impetus by the discovery of the high concentration of estrogens in the urine of pregnant women and in the urine of pregnant mares.3 These discoveries, which provided excellent sources of the estrogens and the means of quantitative determination, were of paramount importance to the isolation of the estrogens and the determination of their structure, as well as to the introduction of an ample supply of estrogenic substances for therapeutic use. The subsequent availability of pure estrogens has permitted an investigation of their role in sex physiology, particularly with respect to the estrous and the menstrual cycle, and of their interrelationships with other internal secretions.
CHEMISTRY OF ESTROGENIC SUBSTANCES
DOISY EA. THE ESTROGENIC SUBSTANCES. JAMA. 1941;116(6):501–505. doi:10.1001/jama.1941.62820060004011