Germinal Stage – Week 1 & 2

•The amnion from the blastocyst forms a thin sac of tissue that surrounds the fetus and is filled with amniotic fluid

•Amniotic fluid is constantly absorbed and replaced with new fluid every 2 to 3 hours

•The embryoblasts change into three cell layers

–Outer – skin, nervous system

–Middle – skeleton, muscles, heart, blood

–Inner – liver pancreas and digestive system

Embryonic Stage – Week 2 to 8

•Remarkable growth

•All embryonic organs become partially formed

•By the end of the first month the primitive heart has begun to beat

•Buds of tissue that will form the arms and legs appear

Fetal Stage – 9 Weeks to Birth

•All primitive organs and structures becoem more differentiated

•Second month distinct hands and feet have formed

•Blood vessels are forming

•12 weeks fetal stomach is producing digestive fluids

•Heart is pumping blood through the fetal arteries and veins

•Kidneys have begun to function

•External genitalia appear

The Fetus (Beginning of the

Ninth Week)

•All organ systems are formed by the end of the eighth week

•Activities of the fetus are growth and organ specialization

•A stage of tremendous growth and change in appearance