Your new resident is nearly an inch long — barely the size of a grape — and weighs just a fraction of an ounce, but he's poised for rapid weight gain now that his basic physical structure is in place. He's also starting to look more and more human. His embryonic "tail" is now completely gone and his body parts — including organs, muscles, and nerves — are kicking into gear.
His eyelids are fused shut and won't open until 27 weeks. He has earlobes, and by week's end, the inner workings of his ears will be complete. His upper lip is fully formed, too, and his mouth, nose, and nostrils are more distinct. The tips of his fingers are slightly enlarged where his touch pads are developing. All major joints — his shoulders, elbows, wrists, knees, and ankles — are working, enabling your baby to move his limbs. As for his heart, it has divided into four chambers now, and the valves have started to develop. External sex organs are there, but won't be distinguishable as male or female for another few weeks.
