Degu. Line drawing of every 6th section through the region of the degu hypothalamus that contains orexin cells. Sections are ordered from rostral (A) to caudal (N). Filled circles indicate locations where both orexin A and orexin B neurons are found. 3V: third ventricle; OC: optic chiasm; f: fornix; mt: mammillothalamic tract; aq: cerebral aqueduct. Scale bar = 500 μm.