fa Original Original <p style="text-align: justify;"><strong>Introduction:</strong> Most mammalians possess an accessory olfactory system, which its first part&nbsp;is called vomeronasal organ (VNO). In this research, we studied the structure of this organ in&nbsp;Azerbaijani red fox.<br> <strong>Methods:</strong> Heads of 10 healthy male fox carcasses were collected from areas around Tabriz&nbsp;and transferred to the laboratory in frozen form or in fixative solution. Biometrical experiments&nbsp;were done, then the maxillary bones cut into 5 pieces, and the pieces decalcified and embedded&nbsp;in paraffin. Then, 7-&mu;m tissue sections were stained with H&E, PAS, and Masson&rsquo;s trichrome&nbsp;methods and explored under light microscope.<br> <strong>Results: </strong>Two ducts of VNO start at the roof of mouth, about 3.17&plusmn;0.28 mm behind the central&nbsp;incisor teeth, extend back into 2 sides of nasal septum and end near the first or second premolar&nbsp;teeth. This organ is surrounded by a hyaline cartilage, which is C-shaped in the first pieces and&nbsp;transform to &ldquo;J&rdquo; shape structure toward the back. The lining epithelium of lumen changes from&nbsp;nonkeratinized stratified squamous epithelium near the valve to pseudostratified columnar in&nbsp;the posterior portions. Presence of bipolar neurons in epithelium of medial wall shows VNO&nbsp;sensory function of smelling. Lamina propria-tunica submucosa in most portions have many&nbsp;serous and mucous secretory units and composed of a loose connective tissue with numerous&nbsp;blood vessels, which secretes pheromone. Also, this is an erectile tissue that can function in&nbsp;association with flehmen reaction to push toward the sensory epithelium of VNO.<br> <strong>Conclusion: </strong>Orifice of VNO of Azerbaijani red fox same more mammalian open in oral&nbsp;cavity. It has 2 type epithelial tissues in end region. Sensory epithelium indicates important role&nbsp;of this organ for received of Pheromones.</p> Anatomy, Histology, Flehmen reaction, Fox, Vomeronasal organ 47 54 http://anatomyjournal.ir/browse.php?a_code=A-10-124-2&slc_lang=fa&sid=1 Hamid Karimi karimi@tabrizu.ac.ir 10031947532846003483 10031947532846003483 Yes Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran. Belal Hassanzadeh 10031947532846003484 10031947532846003484 No Central Lab, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran. Nasser Razmaraii 10031947532846003485 10031947532846003485 No Parasitology Laboratory, Razi Vaccine and Serum Research Institute, Northwest Branch, Marand, Iran.