Histochemical Properties of the Vomeronasal System in Hokkaido Sika Deer (Cervus nippon yesoensis)

The vomeronasal system (VNS) is directly linked to the various behavior and ecology of all animal species, and understanding it might help to prevent deer damage. We therefore histochemically analyzed the accessory olfactory bulb (AOB) and the vomeronasal organ (VNO) that, respectively, function as a primary integrative center and a peripheral receptor organ, in Hokkaido sika deer (Cervus nippon ssp. yesoensis). The AOB consisted of the vomeronasal nerve, glomerular, plexiform, and granule cell layers. We found that G protein α subunit i2 (Gαi2) and o (Gαo) that are, respectively, coupled with vomeronasal receptor type 1 and 2 families were strongly and weakly expressed in the glomerular layer, respectively. These properties of the AOB of sika deer were similar to those of other artiodactyl species, including wapiti. We then explored the sika deer VNO using 21 lectins that bind to each glycan structure. Although various cell types in the VNO had unique lectin binding profiles, all 21 lectins bound to the free border of the sensory epithelium, suggesting that various glycoconjugates are involved in pheromone detection in sika deer via the VNO. Furthermore, the reactivity of some lectins in the sensory epithelium and vomeronasal gland differed from those of roe deer and wapiti. Our findings suggest that the composition of glycoconjugates in the VNO differs among deer species.