Fig 3.4 / Early formation of nervous system. To replace existing photo that is too expensive.
Choice 7 of 7
Human embryo. Colored side view of a 6 week (44 day) old human embryo. The embryo measures 13-15 mm in length and has paddle-like limbs with fingers and toes forming. At this age its eyes (black) have become pigmented. The embryo floats in an amniotic sac, attached to the placenta by an umbilical cord (not clearly seen). Nutrients and oxygen pass from the mother to her embryo through the umbilical cord, while waste products travel in the opposite direction. After eight weeks of development the embryo is called a fetus.