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Olfactory/CNS: developmental separation ?

Teresa Binstock binstoct at essex.hsc.colorado.edu
Wed Jul 26 21:01:48 EST 1995

New study with olfactory/CNS significance:

Development of the olfactory nerve: its relationship to the craniofacies. 
               Braddock SR et al Teratology 51.252-6 1995

I and others spend much time in researching and thinking about the
development of the human CNS and possible roles of vomeronasal organ,
accessory olfactory nerve, and pheromones in influencing sexual behavior
as well, perhaps, as sexual and gender orientations. 
     Certainly interrelated with these subjects are the roles of
olfactory and other extra-hypothalamic GnRH neurons and their
interactions with various immune processes. 

My most recent post prior to this message mentioned the extracellular
matrix and some of its constituents and/or related factors such as
proteoglycans, hyaluronic acid, arachadonic acid, etc. These substances
seem to have causal influence within the immediate environment of
developing neurons within the olfactory placode as they migrate into the
mammalian forebrain. 
     On this level we seem to be getting close to how enzymatic or other
genetic/molecular processes might "clip" a pheromone response element in
one direction or another; and if the process were dysregulated and
reversed at a key developmental time, then the creature's sexual
orientation might be opposite what is most common for its X,X basis or
for its X,Y basis.

           *****                               *****

Given this context, the newly published study cited above caught my eye,
and in calling attention to this study, I'd like to offer a quote from
the abstract:

"...it is concluded that both olfactory receptor cells and olfactory
nerves are present in arhinencephaly, that the olfactory nerves did not
make contact with the brain in these cases, that the presence of
olfactory nerves is independent of the severity of the central nervous
system malformation, and that the shape of the nasal structures is not
dependent on the presence of the olfactory nerve."

To borrow a long-ago coined phrase, this passage is "frought with
significance", including the possible separation of (i) the CNS, and (ii)
basic molecular encoding of vomeronasal and pheromonal responses to male-
type and female-type pheromones. 
     Is it possible that sexual orientation is so fundamental that it
preceeds and transcends the CNS, thereby allowing the CNS to stand as an
activational mechanism but not as a source of primary sexual orientation?

           *****                               *****

If this theoretical notion were shown to have validity, then looking
within many areas of the CNS of primates and humans for primary aspects
of genetic/molecular determinants of sexual orientation might be a replay
of the old song "lookin' for love in all the wrong places..."

Note that I stress, "it ain't necessarily so" 

             but then again it ain't necessarily not so, either.

CONCLUSION: The Braddock et al study is highly recommended.

Teresa Binstock, Researcher
Developmental & Behavioral Neuroanatomy

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