Labeled Estradiol. Estradiol (known as a-Estradiol or 17 a-Estradiol) is a biologically active estrogen in human breast cancer cells in tissue culture. 17-Εstradiol and its selective receptor, ER-X, are not part of a classical hormone/receptor endocrine system but of a system with important autocrine/paracrine functions in the developing and adult brain. 17-Estradiol may have enormous implications for hormone replacement strategies at the menopause and in the treatment of such neurodegenerative disorders as Alzheimer’s disease and ischemic stroke.Form:White SolidMelting Point:218-220°CSolubility:Methanol