Estrone (E1, and also
oestrone) is an
estrogenic hormone secreted by the
ovary as well as
adipose tissue with the chemical name of 3-hydroxyestra-1,3,5(10)-triene-17-one and the chemical formula C
18H
22O
2. Estrone is an odorless, solid crystalline powder, white in color with a melting point of 254.5 °C and a specific gravity of 1.23. Estrone is one of several natural
estrogens, which also include
estriol and
estradiol. Estrone is the least abundant of the three
hormones; estradiol is present almost always in the reproductive female body, and estriol is abundant primarily during
pregnancy.