Getting to the bare bones of fertility

Reproductive organs are known to produce hormones that affect bone remodeling, perhaps best illustrated by the fact that ovarian failure leads to bone loss and osteoporosis in post-menopausal women. An intriguing new role for the skeleton has been highlighted by a recent study by Franck Oury et al.¹ showing that there is a reciprocal relationship in which bone can regulate fertility. The authors show that, in mice, the bone-derived hormone osteocalcin regulates testosterone production by the testes. Mice lacking osteocalcin show reduced testis weight and sperm counts and also produce less offspring than wild-type controls. This demonstration that the skeleton acts as an endocrine regulator of reproduction might provide insights into the underlying mechanisms involved in male infertility. We asked three experts to comment on how this study enhances our understanding of the relationship between bone and reproduction.