Figure 4.
Premenopausal women (A) demonstrate normal cycling hormones and autocrine-paracine levels of activin/BMP, resulting in normal adult bone cell differentiation and bone turnover. (B) Peri-menopausal decreases in inhibin B (InhB) increase circulating FSH and local activin/BMP tone, increasing cell differentiation and turnover. (C) Postmenopausal decreases in InhA and estradiol amplify increases in cell differentiation and dramatically increase bone turnover. FSH, follicle-stimulating hormone.