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Human VNO Function: A Critical Review of Best and Worst Cases, (Shortened and Annotated)

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  • Devin1Neil
    Field tester


    DiscoverXS True Story Teller
    • Jun 2019
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    #1

    Human VNO Function: A Critical Review of Best and Worst Cases, (Shortened and Annotated)

    Here lies my reading for tonight, felt like I should shorten it down and simplify it. Any of my words are in Italics, and the rest are copy-pasted and shortened direct from the source. Feel free to check it out and give it a read, however know its a 30-50 min read. I recommend skimming. Here's a summary of the most interesting parts.



    Structure:


    The existence of a VNO in the human embryo similar to the VNOs of other species is undisputed (Boehm and Gasser, 1993). Numerous reports of a structure identified as the VNO in the nasal septum in adult humans agree that it is a blind ending diverticulum in the septal mucosa opening via a depression (the VNO pit) into the nasal cavity ∼2 cm in from the nostril. The location of this structure is consistent with the location of the VNO in embryos (Trotier et al., 2000) and it has a similar simplified form, with no large blood vessels, cavernous sinuses or supporting cartilage. The structure is reported at least unilaterally in 90% or more of subjects in some reports or in 50% or fewer in other reports. Trotier et al. recently demonstrated that the endoscopic appearance of the VNO pit can vary, unequivocal on one inspection and invisible on a later inspection, or vice versa (Trotier et al., 2000). The real percentage of individuals with at least one VNO pit may thus be underestimated in many studies. It seems highly likely that this structure is the adult human remnant of the vomeronasal organ. Use of the word organ in this context does not presuppose function.

    Best case: The vast majority of human adults have a VNO.

    Worst case: There is a diverticulum of the nasal epithelium which happens to be remarkably consistently located at the expected position of the VNO.

    Opinion: There is an adult human VNO


    Basically it's pretty undisputed that this organ exists, the question is of its remaining function in humans. Microanatomy:
    The epithelium lining the human VNO is unlike that of VNOs in other species and unlike that of olfactory or respiratory epithelium in humans (Moran et al., 1991; Stensaas et al., 1991). There are many elongated cells presenting a microvillar surface to the lumen of the organ but most are not similar to microvillar vomeronasal sensory organs (VSNs) of other species. They have not been shown to have axons leaving the epithelium nor to make synaptic contact with axons in the epithelium, so if they are chemosensitive they have no obvious way of communication with the brain.


    We don't know how (or if) this works in humans, unlike animals there are no direct connections from this organ to the brain that have been found Function: evidence from chemical communication?

    There is fairly clear evidence for chemical communication among humans. The most notable example is a trend towards synchronization of menstrual cycles in women who live together (McClintock, 1971). Stern and McClintock have recently deduced the presence of two substances that can mediate this response when extracts of skin secretions are placed on the upper lip (Stern and McClintock, 1998). Thus, the signals are most likely to be airborne chemicals. The trend towards synchronization arises from either shortening or lengthening of the cycle by secretions produced at different phases of the donor’s cycle [but see the comment by Whitten (Whitten, 1999)]. The substances involved are unknown and although the effect does appear to be chemosensory, there is no evidence that it is due to vomeronasal sensory input. Jacob and McClintock have also recently reported a human behavioral response to odor; changes in mood elicited by androstadienone and 1,3,5(10)16 estratetraen-3-ol (Jacob and McClintock, 2000). These are substances that elicit sexually dimorphic EVGs and are related to skin chemicals claimed to be human pheromones. Jacob and McClintock report the maintenance of a more positive mood in women in the presence of androstadienone under circumstances where control subjects showed an increasingly negative mood. The response cannot be attributed to the vomeronasal system because the stimuli were placed on the upper lip, not confined to the VNO. Grosser et al. also report significantly less negative mood in subjects exposed to androstadienone than in control subjects (Grosser et al., 2000). In their experiments androstadienone was applied directly to the VNO, a much better case for vomeronasal mediation. However, as with the EVG, responses due to stimulation in the region of the VNO are not necessarily mediated by VSNs.

    We can see an obvious effect but cannot necessarily attribute it to the VNO
    Opinion: Methodology of testing is the culprit here, we don't know what necessarily stimulates the VNO and what we just smell. Certain studies with electrostimulation of the VNO show function and I personally believe the VNO does exist and is stimulated by pheros. See below.

    Positive evidence?

    None of the speculations about vomeronasal chemosensory neurons would be worth much consideration if there were not some positive evidence for a non-olfactory, non-trigeminal chemosensory function located in the region of the human VNO. This evidence comes almost exclusively from the work of Monti-Bloch and colleagues. They report an electrophysiological response to application of small amounts of steroid chemicals confined to the VNO region. Because these studies are supported in part by corporations with a commercial interest in exploiting the findings, the results are widely discounted by the academic community. However, they should be evaluated on their merits. There is no serious error in methodology that is obvious from the published papers, so they have to be taken seriously. There is also evidence in these reports for a systemic physiological response to this stimulation and although anecdotal evidence suggests no conscious response in awake human subjects, there is evidence for an alteration of mood. The physiological evidence is critically evaluated in the next section; the behavioral evidence is considered later.




    Abstract. The human vomeronasal organ (VNO) has been the subject of some interest in the scientific literature and of considerable speculation in the popular s
  • Muestereate
    A Stellar Dendrite
    DiscoverXS Posting God
    • Jul 2018
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    #2
    Click image for larger version  Name:	image.png Views:	1 Size:	38.5 KB ID:	113585

    All Gone. There's an amazing amount of genetic material in each of us that is unused. I think some fetuses have tails and we all start off as females too. That doesn't mean my testes are ovaries or that I can swing from trees with my tail.

    I have a hard time classifying the nerve bundle as an organ even in animals. I don't deny there could be an area in the nasal cavity that has steroid receptors. I personally suspect they release some sort of chemical response to our pheromones. We know there is no nerve fiber attachment though. I don't think it's part of the nervous system though. More likely hormonal, maybe one of those amylases conversions.

    I've studied and posted on how different tissues in the body convert pregnenolone into different hormones depending on the type of tissue doing the converting. I have trouble calling those tissues organs too. I'm still theoretical on how these work though I think some work differently than others so any nasal tissue isn't going to explain it all. The whole pheromone and putative routing will be much more complex.

    Chart, by the way, is 2013 fetal autopsies, gross.

    More recent research

    Last edited by Muestereate; 07-28-2019, 08:35 AM.

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