From babycenter, here is how the baby is growing inside at 17 weeks:
Your baby's skeleton is changing from soft cartilage to bone, and the umbilical cord — her lifeline to the placenta — is growing stronger and thicker. Your baby weighs 5 ounces now (about as much as a turnip), and she's around 5 inches long from head to bottom. She can move her joints, and her sweat glands are starting to develop.
We will be having another OB appointment this Friday evening and I'm so excited to know how we're both doing. :-)