The embryo is the size of a lentil this week. If you could see inside yourself, you'd find the fetus has an oversized head in proportion to its body. The embryo's facial features are forming with dark spots where the eyes are, openings where the nostrils will be, and pits to mark the ears.
Protruding buds that will become the arms and legs are even more noticeable now. The embryo's hands and feet look like paddles. Other developments include the growth of the pituitary gland and muscle fibres. You can't hear it yet, but the heart (which has divided into the right and left chambers) is beating at about 150 beats a minute -- twice the rate of yours.