Highly speculative experimental claims

Is it a boy or a girl? Expecting parents
may be accustomed to this question, but contrary to what they may
think, the answer doesn’t depend solely on their child’s sex
chromosomes.

Scientists at the European Molecular
Biology Laboratory (EMBL) in Heidelberg, Germany and the UK’s Medical
Research Council’s National Institute for Medical Research (NIMR) have discovered that if a specific gene located on a non-sex
chromosome is turned off, cells in the ovaries of adult female mice
turn into cells typically found in testes.

Their study, published in the journal Cell,
challenges the long-held assumption that the development of female
traits is a default pathway.

If it had a gene called Sry, which is
located on the Y chromosome, it was thought that an embryo would
develop into a male, if not, then a female. But in adult animals it is
the male pathway that needs to be actively suppressed, the researchers
discovered.

A gene called Foxl2, which is located on an
autosome — a chromosome other than the sex chromosomes — and
therefore present in both sexes, was known to play an important role in
the female pathway, but its precise function remained elusive. The
researchers turned this gene off in the ovaries of adult female mice.

“We were surprised by the results,” says
Treier, “We expected the mice to stop producing oocytes, but what
happened was much more dramatic: somatic cells which support the
developing egg took on the characteristics of the cells which usually
support developing sperm, and the gender-specific hormone-producing
cells also switched from a female to a male cell type.”

Thus, the scientists discovered that Foxl2
plays a crucial role in keeping female mice female. Teaming up with the
group of Robin Lovell-Badge at the NIMR, they were able to decipher
together the underlying molecular mechanism.

These findings will have wide-ranging
implications for reproductive medicine and may, for instance, help to
treat sex differentiation disorders in children, for example where XY
individuals develop as females or XX as males, and to understand the
masculinising effects of menopause on some women.

This experiment clearly boosts the notion
that gender is a malleable concept. Steve Connor, science editor of the
Independent, commented: “The findings suggest that being male or female
is not a permanently fixed state but something that has to be
continually maintained in the adult body by the constant interaction of
genes to keep the status quo – and the gender war – from slipping in
favour of the opposite sex.”

Professor Lovell Badge concurred: “it may
eventually remove the need for surgery in gender-reassignment
treatment… It’s still very speculative, but it’s possible that this
approach could produce an alternative to surgery and the removal of
gonads – ovaries and testes.” ~ Science Daily, Dec 11; Independent, Dec 11

Michael Cook
gender
sex reassignment

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Michael Cook

Michael Cook edits BioEdge, a bioethics newsletter, and MercatorNet, an on-line magazine whose focus is human dignity. He writes from Sydney, Australia.

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