The presence of the human Vomeronasal Organ (VNO) and its function
The vomeronasal organ (VNO), also known as Jacobson’s organ, is an auxiliary olfactory sense organ found in many animals. It is also the first stage of their accessory olfaction systems and is the sense organ involved in the Flehman response. In many mammalian species, a portion of the olfactory neuroepithelium is discretely organized into a VNO . Animals use their VNOs to come into contact with chemosensory cues such as pheromones released by other individuals. In mammals, the VNO contains chemosensory receptor cells that bind to pheromones. The binding of pheromones to receptor cells in the VNO provides information about the physiological status of the emitter and facilitates and regulates interactions and behaviors such as sexual behaviors .
Rodents have highly developed VNOs but this structure has been shown to be absent in some primate species including humans . Regardless, the presence of human VNO and its function has been the subject of considerable interest in science literature and has caused several speculations. In this paper, I will attempt to address the question of whether the VNO is present in humans and its functional significance involving neural and hormonal regulation. This will be done by discussing the evidences for and against human VNO presence and the possible functions of human VNO as put forward by scientific research. The paper will also discuss the significance of pheromone communication in humans facilitated by the VNO and its effect on their behaviors, especially reproductive behaviors.
In order to answer the questions stated above, this paper will address questions surrounding the presence and the nature of neural pathways involving the VNO that are mediated by steroid hormones in humans. The possible connections between the VNO and different areas of the human brain will also be discussed. The paper will also explore the presence of receptor cells that bind pheromones or steroid hormones in the VNO or the human brain in order to investigate the possible sensory functions of human VNO and its effect on behavior.
It has been generally accepted that the VNO is not always present and assumes a vestigial role with no functional significance in humans . However, some scientific research support the presence of the VNO in humans. Boehm N et al. discovered the presence of sensory receptor-like cells in human fetal VNOs . Garcia-Velasco et al. randomly selected 1000 human subjects and evaluated them for the presence of VNOs and discovered that VNOs were present in almost every subject tested . Such findings suggest that the VNO present in human brains may have functional significance that involves neural and hormonal regulations.
Research by Berliner et al. demonstrates that the human VNO is a functional organ, which influences the hypothalamic pituitary axis through...