With the advances of immunohistochemistry in combination with confocal microscopy, airway sensory receptor end-organs can now be examined and evaluated objectively. Based on their 'neurochemical coding', morphology, location and origin, three sensory receptor end organs are currently morphologically well-characterised: smooth muscle-associated airway receptors (SMARs), neuroepithelial bodies (NEBs) and visceral pleura receptors (VPRs). The present information on the functional morphological and neurochemical characteristics of these sensory receptors, leads to important conclusions about...