The embryonic stage of prenatal development is the second stage of the process, following the germinal stage. It begins around the second week after conception and lasts until about the eighth week. Here are the steps involved in this stage:

1. **Formation of the Embryo**: After the fertilized egg, or zygote, divides and grows into a ball of cells, it becomes a blastocyst and implants itself into the wall of the uterus. The cells then differentiate into an inner group, which will become the embryo, and an outer group, which will become the placenta.

2. **Development of the Amniotic Sac**: The amniotic sac begins to form. This fluid-filled sac will protect and cushion the developing baby throughout the pregnancy.

3. **Formation of the Primitive Streak**: This is the beginning of the development of the nervous system. The primitive streak is a structure that will develop into the brain and spinal cord.

4. **Formation of the Heart and Blood Vessels**: Around the third week, the heart begins to form and starts beating and pumping blood by the end of the week. The blood vessels also start to develop at this stage.

5. **Development of the Ectoderm, Mesoderm, and Endoderm**: These are the three primary layers of cells in the embryo. The ectoderm will become the skin and nervous system, the mesoderm will become the bones, muscles, and cardiovascular system, and the endoderm will become the respiratory and digestive systems.

6. **Formation of the Neural Tube**: The neural tube, which will become the brain and spinal cord, begins to form.

7. **Development of the Head, Limbs, and Organs**: By the end of the embryonic stage, the beginnings of all the major organs have formed, and the embryo's head and limb buds start to develop.

8. **End of the Embryonic Stage**: By the end of the eighth week, the embryo is about an inch long and has a distinct, though still very primitive, human appearance. The embryonic stage is followed by the fetal stage, which lasts until birth.

Remember, these steps are a simplified explanation of a very complex process. Each step involves intricate biochemical and physical processes.

Question

The embryonic stage of prenatal development is the second stage of the process, following the germinal stage. It begins around the second week after conception and lasts until about the eighth week. Here are the steps involved in this stage:

1. **Formation of the Embryo**: After the fertilized egg, or zygote, divides and grows into a ball of cells, it becomes a blastocyst and implants itself into the wall of the uterus. The cells then differentiate into an inner group, which will become the embryo, and an outer group, which will become the placenta.

2. **Development of the Amniotic Sac**: The amniotic sac begins to form. This fluid-filled sac will protect and cushion the developing baby throughout the pregnancy.

3. **Formation of the Primitive Streak**: This is the beginning of the development of the nervous system. The primitive streak is a structure that will develop into the brain and spinal cord.

4. **Formation of the Heart and Blood Vessels**: Around the third week, the heart begins to form and starts beating and pumping blood by the end of the week. The blood vessels also start to develop at this stage.

5. **Development of the Ectoderm, Mesoderm, and Endoderm**: These are the three primary layers of cells in the embryo. The ectoderm will become the skin and nervous system, the mesoderm will become the bones, muscles, and cardiovascular system, and the endoderm will become the respiratory and digestive systems.

6. **Formation of the Neural Tube**: The neural tube, which will become the brain and spinal cord, begins to form.

7. **Development of the Head, Limbs, and Organs**: By the end of the embryonic stage, the beginnings of all the major organs have formed, and the embryo's head and limb buds start to develop.

8. **End of the Embryonic Stage**: By the end of the eighth week, the embryo is about an inch long and has a distinct, though still very primitive, human appearance. The embryonic stage is followed by the fetal stage, which lasts until birth.

Remember, these steps are a simplified explanation of a very complex process. Each step involves intricate biochemical and physical processes.

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