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Question about Vomeronasal Organ (VNO)?

*Hemidactylus* hemidactylus at my-deja.com
Tue Aug 3 11:59:58 EST 1999

In article <7o3432$8mk at dfw-ixnews19.ix.netcom.com>,
  flefever at ix.netcom.com(F. Frank LeFever) wrote:
> About time for me to pop off on the basis of dim memories of stuff
> possibly not well understood (by me) when I read it, and possibly
> revised by later work, anyway.
> Anyway, for what it's worth, I came to the conclusion, after a book by
> C. Judson Herrick sent me (c. 30-40 yrs ago?) to the comparative
> anatomy literature then available, that while one might consider the
> rhinal cortex (indeed, the whole cerebral cortex, ultimately, but
> rrhinal cortex immediately?) an outgrowth of the olfactory nerve
> (hypertrophy of its central ganglion), the amygdala (or some parts of
> it) could in the same sense be considered an outgrowth of the
> vomeronasal organ.

The amygdala is a nucleus involved with (among other functions I'd imagine)
social interactions and aggression, right? It's been a while since I've
studied some of the neurochemistry and assumed localization of function for
the limbic system and the basal ganglia and sundry assorted regions.
Sometimes I feel like I'm running in place.

It would seem reasonable that smell or pheromone reception and social
interaction would be linked, but I'd think that this is a murky issue with
humans. We're not quite ants.

Looking through my stack of papers, I noticed I have two which are relevant
to the VNO and pheromones, if any lurkers are interested:

Weller A. 1998. Communication through body odour. Nature (392): 128-7 (news
and views)

Stern K and McClintock MK. 1998. Regulation of ovulation by human pheromones.
Nature (392): 177-9 (letters to nature)

I'm not quite sure to make of these articles, because I've heard of some
controversy surrounding these ideas.

> Conceivably, it might persist in phylogeny even after its ancestral
> point of origin atrophied.

We have several "vestiges". From reading your posts in the past, I've noticed
you have some background in immunology. The vermiform appendix is a vestige,
yet has some minor immunological function as I recall. Why not assign some
minor (relatively non-essential?) duty to something that's literally just
hanging around for the ride?

I noticed that some vertebrate species might have a cranial nerve O (terminal
nerve), but I'm not sure whether humans ever exhibit this as a "vestige" or
throwback to the embryology of ancestors. I guess this qualifies as trivial
pursuit biology :-)

> In the absence of a vomeronasal organ, are there alternative routes for
> incoming pheromone signals?  One thinks of analogous non-geniculate and
> even non-retinal routes for photoperiod synchronization and other
> "non-visual" aspects of light influences on neuroendocrine activity and
> behavior. Indeed, we don't even have to invoke the idea of light
> filtering through your thinning hair to the pineal gland: one recent
> study suggests that light to the back of the leg (behind the knee) can
> be effective for something or other (was it SAD treatment? re-setting
> circadian rhythm?  I forget.)

It's been quite a while since I was familiar with the intricacies of the
various biological rhythms. I covered this in ecology, but it was in an
abnormal psych course where I wrote a paper on this stuff. Basically, as I
recall, it was photons incident on the retina which triggger some
neurochemical cascades involving both the suprachiamsatic nucleus of the
hypothalamus and the pineal gland (heavy hand waving here :-)). It all
centers on the level at which melatonin is being enzymatically produced (via
an indole pathway) in the pineal.

Biological rhythms might have a stricter control on the psychophysiological
processes of other species, and just like pheromones, I'd ask whether this is
as important in humans anyway.

Of course SAD is an issue. I recall the use of light banks for 15 minutes in
the morning as a means of ameliorating the symptoms of SAD. It's been so long
since I've read about the circadian rhythms that I'm sure all my info is
somewhat out of date.

As far as your mention of the light spot on the head, I think some squamates
(either snakes or lizards) have a "third eye" which is apparent from a slight
discoloration on top of the head. I'm not sure how widely this trait spreads
through the reptiles.

> In <7nq0ut$rp5$1 at nnrp1.deja.com> *Hemidactylus*
> <hemidactylus at my-deja.com> writes:
> >
> >In article <19990725205613.06206.00001365 at ng-fu1.aol.com>,
> >  holson1000 at aol.com (Howard Olson) wrote:
> >> >Does anyone know if reconstruction of the nasal pathways (a nose
> job) would
> >> >typically damage or destroy the Vomeronasal Organ (VNO)?
> >> >
> >> >Thanks.
> >>
> >>   It would obviously depend on the extent of the surgery. But the
> real problem
> >> is the fact that many medical experts did not believe in a human VNO
> until it
> >> was proven
> >> that humans did have pheromones like the axillary androgens. Hope
> that
> >> helps.....
> >>
> >>
> >
> >One question I've had, which come from something I picked up in a
> comparative
> >anatomy class, is whether humans have cranial nerve O (aka the
> terminal
> >nerve). I think, if memory serves me correctly, the terminal nerve is
> >developed in elasmobranchs but that there is controversy over whether
> such a
> >cranial nerve exists in mammals or humans especially. This might fit
> in with
> >the VNO / pheromone issue. I've had a literature search on menstrual
> synchony
> >on the backburner, so I should motivate myself to explore this
> interesting
> >issue (ie- pheromones and human physiology/behavior).
> >
> >The terminal nerve question really eats at me though, since I'm
> interested in
> >things that are conserved in evolution (ie- homologies). Do we share
> this
> >cranial nerve O feature with our elasmobranchian fellow vertebrates or
> has
> >our "lineage" (sic) abandoned this.
> >
> >--
> >Scott Chase
> >
> >
> >Sent via Deja.com http://www.deja.com/
> >Share what you know. Learn what you don't.

Scott Chase

Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.

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