What are the key stages of fetal development?

The key stages of fetal development are the germinal stage, embryonic stage, and the fetal stage.

The first stage of fetal development is the germinal stage, which begins at conception and lasts until the fertilised egg implants in the uterus, typically around two weeks later. During this stage, the fertilised egg, or zygote, undergoes rapid cell division and forms a blastocyst, a ball of cells that will eventually become the embryo. The blastocyst also produces the placenta, which will provide oxygen and nutrients to the developing fetus.

The second stage is the embryonic stage, which lasts from the end of the germinal stage until about the eighth week of pregnancy. During this stage, the major organs and systems of the body begin to form. This includes the neural tube, which will become the brain and spinal cord, the heart, and the gastrointestinal tract. The embryo also begins to form structures that will become the face and develops limb buds that will grow into arms and legs. This stage is particularly critical for the development of the fetus, as any damage or disruption can lead to major birth defects or miscarriage.

The final stage is the fetal stage, which lasts from the end of the embryonic stage until birth. This is the longest stage of prenatal development and is characterised by rapid growth and maturation of the organs and systems that formed during the embryonic stage. The fetus also begins to move and respond to stimuli, and the brain undergoes significant development. By the end of this stage, the fetus is fully formed and ready for birth.

Each of these stages is crucial for the development of a healthy fetus, and disruptions at any stage can have significant impacts on the health and development of the baby. Therefore, understanding these stages is important for anyone studying human biology or medicine.