Implantation begins the first week and the embryo continues to grow. Structures that will become arms and legs, called limb buds, begin to appear. Blood is beginning to be pumped through fetal circulation. Heartbeat is visible by ultrasound. Fingers and toes begin to form.
Reflex activity begins with the development of the brain and nervous system.
The beginnings of all key body parts are present, although they are not completely positioned in their final locations. Structures that will form eyes, ears, arms and legs are identifiable. Fingers and toes are distinct and have nails. The developing human begins small, random movements, too slight to be felt. The child's heartbeat can be detected with a doppler or heart monitor.