00:01
So how is the genetic sex
of a fetus or eventual
infant determined/
of the 46 chromosomes
and the fertilized eggs
only two of them
are sex chromosomes.
00:15
The rest of them we refer
to them as autosomes
are autosomal chromosomes.
00:21
The two sex chromosomes
include the X chromosome,
which is the larger of the two,
and then the Y chromosome,
which is actually quite small.
00:31
Females contain
two X chromosomes
where each ovum always
has an X chromosome.
00:41
And males, you're going to
have X and Y chromosomes
so in the male body
50% of the sperm are going
to contain X chromosomes
and 50% of the sperm are going
to contain Y chromosomes.
00:57
So if fertilizing sperm delivers
an X to the fertilized eggs,
then it will contain an X X
and the embryo will
develop ovaries.
01:08
However, if the fertilizing
sperm delivers a Y chromosome,
then the fertilized
egg will contain X Y
and the embryo will
develop testes.
01:20
The development of testes
is caused by the SRY gene,
which is a master switch
on the Y chromosome.
01:29
It's important for
the initiation of
testes development and maleness.
01:35
Because it is the
father or the sperm
that will deliver the X or the Y
and because the ovum always
contains X chromosomes.
01:46
It is the father
that determines the sex of
a child during conception.