[Magdalen] Sex determination (was something else)

[Rick Mashburn]

I was horrible at science in school but isn't it really genetic? The fetus
is either xx or xy from conception, right? Wouldn't that control the
physical development?

Peace, Rick
On May 6, 2016 8:32 AM, "James Handsfield" <jhandsfield at att.net> wrote:

> There’s a difference between the genetics and the anatomical development
> of an embryo or fetus.  You are right that an embryo is male or female in
> most cases.  Genetic confusion does occur, but it’s usually fatal long
> before term.
>
> The argument that an embryo or fetus becomes a different sex in
> development is also mistaken.  It’s based on the long discredited idea that
> ontogeny recapitulates phylogeny.  The anatomical sex differences are
> homologous in that they arise from the same embryonic structures.  There
> are two embryonic reproductive systems in mammals - the Malphigian system
> and the Wolffian system.  The Malphigian system becomes dominant in males
> and the Wolffian system in females, but both systems exist in both sexes.
>
> Alleluia!  Christ is risen!
>
> James Handsfield
> jhandsfield at att.net
>
> > On May 6, 2016, at 4:02 AM, Sibyl Smirl <polycarpa3 at ckt.net> wrote:
> >
> > That's not the way that I learned it. At least, 99.9% of the time,
> there's an egg and a sperm.  The sperm contains either an x chromosome or a
> y chromosome, not both.  The egg contains an x chromosome, one of two
> possibles (the mother has two matching ones, which divide to produce the
> egg.)  Conception occurs when the egg and the sperm meet: an X matches with
> a y, or with another x, so that if it happens to be a Y sperm, conception
> results in an XY (male) combination, and if it's an X sperm, you get an XX
> combination (female).  So from the moment there's a fertilized egg, it's
> either a girl or a boy, even if it's only one or a few cells, and you can't
> yet tell by looking until much later, unless you want to kill it and have
> an electron microscope handy.
>
>