a role with chemoreceptors in hypoxia detection. This is best supported by the presence of an oxygen-sensitive potassium channel coupled to an oxygen sensory protein in the rabbit lumenal membrane. They are hypothetically involved in regulating localized epithelial cell growth and regeneration through a paracrine mechanism, whereby their signaling peptides are released into the environment. In addition, they contain neuroactive substances which are released from basal cytoplasm. These substances induce autonomic nerve terminals or vasculature in the deep lamina propria. Role in fetal lung In the fetal lung, they are frequently located at the branching points of airway tubules, and in humans are present by 10 weeks gestation. Peptides and amines released by PNEC are involved in normal fetal lung development including branching morphogenesis. The best-characterized peptides are GRP, the mammalian form of bombesin, and CGRP; these substances exert direct mitogenic effects on epithelial cells and exhibit many properties akin to growth factors. Example Specialized groups of neuroendocrine cells can be found at the base of the third ventricle in the brain (in a region called the hypothalamus). This area controls most anterior pituitary cells and thereby regulates functions in the entire body, like responses to stress, cold, sleep, and the reproductive system. The neurons send processes to a region connecting to the pituitary stalk and releasing hormones are delivered into the bloodstream. They are carried by portal vessels to the pituitary cells where they may stimulate, inhibit, or maintain the function of a particular cell type. See also Neuroendocrine tumor Neuroendocrinology Neurohormone Chromophobe cell Melanotroph Chromophil Acidophil cell Basophil cell Oxyphil cell Oxyphil cell (parathyroid) Pituitary gland References External links Nervous tissue cells Endocrine cells