Originally, they were identified in an electron microscopic analysis of the rat trachea (Rhodin and Dalhamn 1956), and subsequently also observed in intestine and gall bladder (Luciano and Reale 1969 Trier et al. Tuft cells, also known as brush cells, are columnar, often flask-shaped cells, and found scattered in the simple surface epithelia of endoderm-derived hollow organs. Our analysis introduces advillin as a selective marker and tool in histological and functional analysis of the alimentary tract tuft cell system. Finally, crossing Avil-Cre transgenic mice with a double-fluorescent reporter mouse line resulted in specific targeting of gastro-intestinal and biliary tuft cells. Advillin expression was no longer detectable in the mucosa of the intestinal and biliary tract from Pou2f3 deficient mice that lack tuft cells. In the glandular stomach, villin and advillin mRNA were present in all epithelial cells, while detectable protein levels were confined to solitary tuft cells. In situ hybridization and immunohistochemistry revealed that advillin expression, unlike villin, was restricted to solitary cholinergic tuft cells in the mucosal linings of the small and large intestine, and in the gall bladder. Here, we report that the villin-related protein, advillin, is a specific tuft cell marker in the gastro-intestinal and biliary tract epithelia. in enterocytes, which limits the use of this gene as a marker and as an experimental tool to genetically target tuft cells. Unfortunately, villin expression is not restricted to tuft cells, but is also prominent e.g. Accordingly, the actin-binding protein, villin, was identified as one of the first tuft cell markers in immunohistochemical analysis. Their name-giving morphological feature is an apical tuft of stiff microvilli. Tuft cells are a rare population of chemosensory cells at the mucosal surface epithelia of hollow organs.