Anti-cancer therapy or advanced age in women can lead to loss of ovarian function (see HERE new positive advances). Cancer therapy effects cause objective health problems, such as sexual changes, obesity and osteoporosis. These changes can be alleviated by hormone replacement therapy, but its use is declining as it has shown negative side effects. The creation of artificial ovaries that could be a substitute for hormone therapy has now been proposed. This has been achieved in rats by creating an artificial ovary that can secrete hormones in the body of another animal with no ovarian function. The transplanted animals showed less fat accumulation and osteoporosis than rats with healthy ovaries or treated with hormones (see further information in NATURE, HERE ).