Hormones are influencing your unborn baby's development and the ovaries or testes now begin to form. The testes will gradually descend but their structural development won't be complete until your child hits puberty. The ovary will produce eggs (see You are 20 Weeks and 6 Days) but these will remain in the early stages of development.
A minute genital tube forms the external genitalia but each sex appears the same at this stage. This is not entirely surprising since the phallus is only 0.09 in (2.5 mm) long. Your baby's bladder and rectum have now separated. The kidneys will take some time to fully develop: two buds grow up from the bladder to the tissue that will become the kidneys, one on each side. These so-called uteric buds form the ureters-the tubes that transport urine from the kidney to the bladder. The ureteric bud must successfully fuse with the kidney tissue in the pelvis. As the ureteric buds expands upward, the early kidneys developing in the pelvis will move upward to lie in the abdomen.