Endocrine glands are ductless glands that secrete their hormones directly into the blood. These hormones act like chemical messengers because when they are transported to target cells, they have a profound effect. For example, one hormone from the pituitary gland called human growth hormone or H.G.H. is secreted into the blood and acts on bone cells at puberty which causes them to divide resulting in growth. Some other examples of endocrine glands in the body include the pituitary gland, the thyroid gland, adrenal glands, Islets of Langherhans(on the pancreas), parathyroids, hypothalamus, ovaries and testes. Exocrine glands contain ducts which transport their secretions to where they are needed in the body cavity, without the assistance of the blood to transport them. Digestive glands are examples of exocrine glands. One example--the salivary glands in the mouth, secrete saliva directly into the mouth once the nervous system senses the presence of food. This moistens food and initiates digestion of starch. Other examples are sweat glands which have ducts that lead to pores on the surface of the skin and mammary glands which secrete milk in female mammals to nourish their young. One important point is that the proper functioning of both endocrine and exocrine glands are necessary to maintain homeostasis.