Erythropoietin EPO kidney Extraglomerular mesangial cells Stimulate erythrocyte production peptide Follicle-stimulating hormone FSH anterior pituitary gonadotrope cAMP In female: stimulates maturation of Graafian follicles in ovary . In male: spermatogenesis , enhances production of androgen-binding protein by the Sertoli cells of the testes peptide Gastrin GRP stomach , duodenum G cell