Endocrine gland Endocrine gland Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct. The major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus and adrenal glands. The hypothalamus and pituitary gland are neuroendocrine organs. The pituitary gland hangs from the base of the brain by a stalk and is enclosed by bone. It consists of a hormone-producing glandular portion (anterior pituitary) and a neural portion (posterior pituitary), which is an extension of the hypothalamus. The hypothalamus regulates the
Uropygial gland nine families of birds lack a uropygial gland, mostly the ones unable to fly or the ones that produce powder down for feather maintenance. These include kiwis ("Apterygidae"), emu ("Dromaiidae"), ostriches ("Struthionidae"), rheas ("Rheidae"), cassowaries ("Casuariidae"), mesites ("Mesitornithidae"), bustards ("Otididae"), pigeons and doves ("Columbidae"), amazon parrots ("Psittacidae"), frogmouths ("Podargidae"), and woodpeckers ("Picidae"). These birds typically find other means to stay clean and dry, such as taking a dust bath. Researchers have been unable to correlate the presence or absence of the uropygial gland with factors such as distribution, climate, ecology, or flightlessness. The uropygial gland secretes an oil (preen oil)