Mouse anti-Human IL8 monoclonal antibody for IA. Estrone is one of the three naturally occurring estrogens, the others being estradiol and estriol. Estrone is produced primarily from androstenedione originating from the gonads or the adrenal cortex. In premenopausal women, more than 50% of the estrone is secreted by the ovaries. In prepubertal children, men and non supplemented postmenopausal women the major portion of estrone is derived from peripheral tissue conversion of androstenedione. Interconversion of estrone and estradiol also occurs in peripheral tissue. Bioassay data indicate that the estrogenic action is much less than estradiol. Estrone is a primary estrogenic component of several pharmaceutical preparations, including those containing conjugated and esterified estrogens. In premenopausal women estrone levels generally parallel those of estradiol. After menopause estrone levels increase, possibly due to increased conversion of androstenedione to estrone.