A paracrine hormone of skeletal muscle acts as an endocrine signal for the synthesis of a sex hormone. Scientists at McGill University have observed in mice how myostatin, which inhibits the development of muscle mass to control its growth, also stimulated the production of the pituitary follicle-stimulating hormone (FSH), modulating ovarian function. The hypothalamus-pituitary-gonadal axis could include an additional element through a yet unknown role in muscles.