<P> Estrogen has anti-inflammatory properties and helps in mobilization of polymorphonuclear white blood cells or neutrophils . </P> <P> Estrogens are implicated in various estrogen - dependent conditions, such as ER - positive breast cancer, as well as a number of genetic conditions involving estrogen signaling or metabolism, such as estrogen insensitivity syndrome, aromatase deficiency, and aromatase excess syndrome . </P> <P> Estrogens, in females, are produced primarily by the ovaries, and during pregnancy, the placenta . Follicle - stimulating hormone (FSH) stimulates the ovarian production of estrogens by the granulosa cells of the ovarian follicles and corpora lutea . Some estrogens are also produced in smaller amounts by other tissues such as the liver, adrenal glands, and the breasts . These secondary sources of estrogens are especially important in postmenopausal women . Fat cells produce estrogen as well . </P> <P> In females, synthesis of estrogens starts in theca interna cells in the ovary, by the synthesis of androstenedione from cholesterol . Androstenedione is a substance of weak androgenic activity which serves predominantly as a precursor for more potent androgens such as testosterone as well as estrogen . This compound crosses the basal membrane into the surrounding granulosa cells, where it is converted either immediately into estrone, or into testosterone and then estradiol in an additional step . The conversion of androstenedione to testosterone is catalyzed by 17β - hydroxysteroid dehydrogenase (17β - HSD), whereas the conversion of androstenedione and testosterone into estrone and estradiol, respectively is catalyzed by aromatase, enzymes which are both expressed in granulosa cells . In contrast, granulosa cells lack 17α - hydroxylase and 17, 20 - lyase, whereas theca cells express these enzymes and 17β - HSD but lack aromatase . Hence, both granulosa and theca cells are essential for the production of estrogen in the ovaries . </P>

What structures are responsible for the production of estrogen
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