Size of the Vomeronasal Organ in Wild Microtus

The structure and function of the mammalian vomeronasal organ (VNO) have been the focus of numerous studies (e.g., Adams and Weikamp, 1984; Vaccarezza et al., 1981). Functionally, this chemosensory epithelial structure has been linked to various behaviors such as mate-finding and aggressive interactions (Powers and Winans, 1975; Wysocki and Lepri, 1991). In mammals, the evidence that VNOs function as a pheromone receptor has derived from experimental data. Determinants of VNO size are less well-understood, but have been hypothesized to include hormonal factors (Segovia and Guillamon, 1982, 1993.). It is therefore possible that morphology of the VNO may vary with gonadal development.