Addendum #4 re:
Teresa's hypothesis concerning S/O & G/O and variations.
THREE DOMAINS OF NASAL CHEMO-PERCEPTION
Abstract: Nasal sensing of chemo-molecules has long been
known to have three routes of signal processing: olfactory,
vomeronasal, and trigeminal (0); however, sexually
significant chemo-signals (sscs) are usually conceived as
occurring in olfactory and vomeronasal domains, despite the
fact that some such sscs may be perceived through trigeminal
routes receiving input from immunological tissues of the
nasal mucosa (see below).
1. MHC & T-Shirts:
A recent article by Wedekind et al utilized females'
perception of T-shirts that had been worn by males as a basis
for determining MHC-related responses to chemo-signals (1).
MHC-linked findings were clear, and the authors' introduction
and discussion are a concise review of MHC-related mate-
choice literature. Yet even as they use the words "odour" and
"scent" in ways suggesting "smell", their discussion suggests
awareness that olfactory and vomeronasal processes may not be
the only possibility, "Our findings show that some
genetically determined odour components can be important in
2. Expanding the Concept:
Recently, I set forth a related hypothesis: (i) the
immunological tissue of the nasal mucosa is a third route for
sexually significant chemo-perception, (ii) MHC-based
surveillance (as in mate-choice or T-shirt selection) resides
in the Antigen-Presenting Cells (APCs) of the nasal mucosa,
(iii) a next link in the signaling is to T-cells, and (iv)
for many individuals, sexual- and gender-orientations (S/O,
G/O) may be a function of immunological tissues in the nasal
3. Evolutionary consideration:
The yeast Saccharomyces Cerevisiae (ySC) offers clues.
Vertebrates have bodies and MHC/Ig immune systems, ySC do
not; yet ySC have clear "his & her" sexual mechanisms, with
many components remarkably similar to human molecules. For
instance, ySC's alpha-factor mating pheromone is very much
like GnRH (2), and the a-factor and alpha-factor pheromones
have sexually dimorphic receptors labeled ste2 and ste3 (3).
Similarly, human T-cells can express GnRH and are matured in
thymic tissue (i) having ste2 and ste3 as cell surface
molecules, and (ii) utilizing H-Y antigen (in XY males) or
its absence (in XX females) as part of establishing self and
not-self determinations (4-7).
The evolutionary preservation of mating-related
components suggests that certain components of yeast sexual-
interaction are present and functioning in humans.
4. The third route of nasal awareness:
The pathway most closely paralleling yeast mating and
chemo-signaling is from the evolutionarily newer APCs of the
nasal mucosa toward ste2- and ste3 in human T-cells, with
the membrane-spanning "zeta" chain an important link (8). In
addition to T-cells, other immune cells provide additional
influences capable of affecting S/O and G/O.
In summary, via trigeminal routes, immune tissues of the
nasal mucosa are bidirectionally, neurally interconnected
with the brain (9) and, along with olfactory and vomeronsal
sensations, provide three functionally overlapping but
differing domains of chemo-signal perception (0), with the
trigeminal route and its immunological afferents possibly
serving as a substrate for S/O and G/O (10).
Collected Writings of Teresa C. Binstock
permission hereby granted
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so: Internet Postings via bionet.immunology and other
newsgroups and listservers, March 1-6, 1996.
ti: Teresa's S/O and G/O hypothesis (and addenda).
Teresa C. Binstock
Researcher in Developmental & Behavioral Neuroanatomy
Denver CO USA
Teresa.Binstock at uchsc.edu