The thyroid gland secretes two hormones into the blood, namely thyroxine and tri-iodothyronine (T3) . The corpus luteum secretes progesterone which helps in maintaining pregnancy, the anterior pituitary secretes six major hormones which are prolactin, growth hormone, adrenocorticotropic hormone, luteinizing hormone, follicle-stimulating hormone and thyroid-stimulating hormone each hormone having different roles. The posterior pituitary secretes oxytocin and vasopressin where the former stimulates uterine contractions whereas the latter helps in osmotic regulation.