Expression of fibroblast growth factors 18 and 23 during human embryonic and fetal development.

Fibroblast Growth Factor (FGF) 18 and 23 are two recently identified members of the FGF family, a family of structurally related polypeptides with diverse roles in physiological and pathological processes. Studies mostly performed in rodents and chicken have demonstrated that FGF18 is a pleiotropic growth factor involved in the development of various organs, while there are no data supporting a direct role of FGF23 in cell proliferation or differentiation either in physiology or pathology in any species. However, it is now established that FGF23 can be a humoral messenger and an important regulator of phosphate homeostasis and vitamin D metabolism. As a first step towards elucidating the roles of these FGF in human development, we examined FGF18 and FGF23 mRNA expression by in situ hybridization in whole human embryos at 30 days and 8 weeks of gestation (GW) and in specific fetal tissues at different ages. We report a highly restricted expression pattern for both FGF genes in human embryonic development.