The vomeronasal organ is not involved in the perception of endogenous odors.

Chemosensory-based communication is a vital signaling tool in most species, and evidence has recently emerged in support of the notion that humans also use social chemosignals (so-called pheromones) to communicate. An ongoing controversy does exist, however, concerning the receptor organ through which these chemicals are processed. There is a widespread belief that the vomeronasal organ (VNO) is responsible for processing social chemosignals in humans. Here we demonstrate that functional occlusion of the VNO does not change the percept of, sensitivity toward, or functional neuronal processing of a putative human pheromone. Perithreshold and suprathreshold perception of the endogenous chemical androstadienone (AND) were compared, as were positron emission tomography brain activations evoked by AND when the VNO was either occluded or left open. In addition, we compared sensitivity to AND in subjects with an identifiable VNO to those in whom no VNO could be detected. Thus we could examine the effects of the VNO at several different levels of processing. Occlusion or absence of the VNO did not affect either the perceptual measurements or the functional processing of the putative human pheromone, AND. These results provide strong evidence that the human VNO has no obvious function. Pheromonal communication in humans may be conveyed via the main olfactory system.

A rare case of jugular foramen schwannoma arising from Jacobson's nerve.

The jugular foramen (JF) region is a complex area of the cranial base where venous structures such as the jugular bulb and the inferior petrosal sinuses are strictly related to the lower cranial nerves IX, X and XI. The most common tumours include glomus jugulare, schwannomas of the mixed cranial nerves (IX-XI) and meningiomas. Schwannomas involving the jugular foramen are rare neoplasms and in most of the cases are thought to originate from the X cranial nerve. We report a case of a schwannoma of the JF diagnosed at an early stage, allowing radiological and surgical evidence to support its origin from the tympanic branch of the IX cranial nerve. To our knowledge this is the first case reported in the literature of such a tumour.

Enlarged vomeronasal organ in a child: imaging findings.

The vomeronasal organ is a special sensory organ that exists in both animals and humans. It is located on the sides of nasal septum and although it involutes with age, occasionally it may be seen in humans. We present the imaging findings in a child with an enlarged nasal septum whose features we believe are compatible with a vomeronasal organ.

The vomeronasal cavity in adult humans.

We observed the surface of the anterior part of the nasal septum of living subjects using an endoscope. In approximately 13% of 1842 patients without pathology of the septum, the vomeronasal pit was clearly observed on each side of the septum, and in 26% it was observed only on one side. The remaining observations indicated either the presence of putative pits or no visible evidence of a pit. However, repetitive observations on 764 subjects depicted changes over time, from nothing visible to well-defined pits and vice versa. Based on 130 subjects observed at least four times, we estimate that approximately 73% of the population exhibits at least one clearly defined pit on some days. By computer tomography, the vomeronasal cavities were located at the base of the most anterior part of the nasal septum. Histological studies indicated that the vomeronasal cavities consisted of a pit generally connected to a duct extending in a posterior direction under the nasal mucosa. Many glands were present around the duct, which contained mucus. There was no sign of the pumping elements found in other mammalian species. Most cells in the vomeronasal epithelium expressed keratin, a protein not expressed by olfactory neurons. Vomeronasal epithelial cells were not stained by an antibody against the olfactory marker protein, a protein expressed in vomeronasal receptor neurons of other mammals. Moreover, an antibody against protein S100, expressed in Schwann cells, failed to reveal the existence of vomeronasal nerve bundles that would indicate a neural connection with the brain. Positive staining was obtained with the same antibodies on specimens of human olfactory epithelium. The lack of neurons and vomeronasal nerve bundles, together with the results of other studies, suggests that the vomeronasal epithelium, unlike in other mammals, is not a sensory organ in adult humans.