GnRH-I is a small 10 amino acid long peptide (decapeptide) from the hypothalamus. GnRH-I acts at the hypophysis to cause an increase in release of biologically active Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH) in the blood, which in turn stimulate the development of the tests in the growing made animal and the synthesis of male steroids. In the growing female animal the development of the ovaries is stimulated, as is the development of follicles within the ovary, synthesis of female steroids, and ovulation.