when does an embryo become fetus
In the last few weeks of the first trimester, the embryo really starts to take shape. The facial structures begin to form and become recognizable. The neural tube, which will form the brain and spinal cord, develops. Little buds emerge and grow into arms and legs. Around week 8, the embryo becomes a fetus. The kidneys, liver, brain, and lungs are all beginning to function. The fingers and toes are separate and the external genitalia are formed. At 12 weeks, the fetus is about three inches long and weighs about one ounce.