A crucial event that determines whether the embryo will
develop into a male or female occurs in the second half of
week six.
If the Y chromosome is present in the embryo's cells, a gene
within the short arm of the chromosome called SRY will turn
on, initiating a chemical chain reaction that will turn on
other genes and stimulate the production of male hormones.
If the X chromosome is present, or if the SRY gene is
missing from the Y chromosome, the embryo will develop into
a female via mechanisms that are not fully understood.
Note: SRY stands for sex-determining region of
the Y chromosome.
