You have 46 chromosomes in each cell of your body. These are grouped into 23 pairs.
The 23rd pair determines your gender. Females have two X chromosomes, and males have
one X and one Y chromosome.
The gender of a developing baby is
determined at conception, when the embryo has either two XX chromosomes, or an X and
chromosome. Around the 6
th week of the unborn
baby's development, a gene on the Y chromosome of a developing boy tells the fetal
tissue that will form the sex organs to become the testes.
As the testes make testosterone,
the penis, scrotum, and urethra form. Then during the 7th to 8th month of the pregnancy,
the testes descend into the scrotum.
Without the Y chromosome, the fetal
tissue in a female baby that will form the sex organs becomes the ovaries, uterus,
Certain hormones also can affect
the development of the sex organs. These hormones are secreted during the early weeks