['To clarify the localization of cyclooxygenase (COX)-1 and -2 in the nasal cavity of guinea pigs and ascertain their physiological roles.', 'The distribution of the enzymes was investigated using immunohistochemistry.', 'Immunoreactivities for COX-1 and -2 were limited to the nasal glands, and no expression was noted in the surrounding vascular endothelial cells, olfactory glands, respiratory epithelium, olfactory epithelium, submucosal tissue or nerves. To confirm the specificity of the reaction, the kidneys of the same animals were prepared as positive controls. The results demonstrated localization of COX-1 and -2 in uriniferous tubules.'] Is expression of cyclooxygenase-1 and -2 limited to the nasal glands in the guinea pig nasal cavity?