The vomeronasal organ (VNO) is a sensory organ that influences social and/or reproductive behavior and, in many cases, the survival of an organism. The VNO is believed to mediate responses to pheromones; however, many mechanisms of signal transduction in the VNO remain elusive. Here, we examined the expression of proteins involved in signal transduction that are found in the main olfactory system in the VNO. The localization of many signaling molecules in the VNO is quite different from those in the main olfactory system, suggesting differences in signal transduction mechanisms between these two chemosensory organs. Various signaling molecules are expressed in distinct areas of VNO sensory epithelium. Interestingly, we found the expressions of groups of these signaling molecules in glandular tissues adjacent to VNO, supporting the physiological significance of these glandular tissues. Our finding of high expression of signaling proteins in glandular tissues suggests that neurohumoral factors influence glandular tissues to modulate signaling cascades that in turn alter the responses of the VNO to hormonal status.

Keywords: gland, immunohistochemistry, olfaction, pheromone, signal transduction, VNO, vomeronasal