FSH (follicle stimulating hormone) is the central hormone of mammalian reproduction, necessary for gonadal development and maturation at puberty and for gamete production during the fertile phase of life. Together with LH, this gonadotropin is produced and secreted by the pituitary gland as a highly heterogeneous glycoprotein. The FSH receptor belongs to the family of G-protein coupled receptors, complex transmembrane proteins characterized by seven hydrophobic helices inserted in the plasma membrane and by intracellular and extracellular domains of variable dimensions depending on the type of ligand. The intracellular portion of FSH receptor is coupled to a Gs protein and, upon receptor activation by the hormonal interaction with the extracellular domain it initiates a cascade of events that ultimately leads to the specific biological effects of the gonadotropin.