Each of the structures integrating the sense of smell in mammals has a different degree of development, even in the so-called macrosmatic animals, according to the capacity of the olfactory system to detect thousands of different chemical signals. Such morphological diversity implies analogous physiological variation. The study of the accessory olfactory system, also known as the vomeronasal system, is a useful way to analyze the heterogeneity of the sense of smell. Macrodissection and microdissection methods as well as conventional histology and immunohistochemistry protocols were used to study aspects of the vomeronasal organ and the accessory olfactory bulbs in dogs. Observations regarding the end of the anterior part of the vomeronasal duct have been emphasized. Both lectins, Ulex europaeus agglutinin I and Lycopersicum esculentum agglutinin, and one G protein, Gαi2, show a similar pattern of binding in the sensory epithelium of the vomeronasal organ and in the vomeronasal nerve and glomerular layers of the accessory olfactory bulb, whereas the expression of protein Gαo was not observed. Taken together, our results emphasize the contribution of comparative data to our understanding of the vomeronasal system function. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.