Week 11 Organs such as liver begin to function. Week 12 Breathing begins with a lung. The fetus sucks his thumb. The muscles and skeleton are matured. The nervous system begins some control.
Blood vessels develop rapidly.
Week 15 Hands grasp and feet kick. Week 16 All human organs and structures are completely formed. Week 19 Eyebrows, eyelashes, head hair are formed. The fetus now has a regular schedule of sleeping, turning, sucking, and kicking. The skeleton is developed rapidly.