What is the developmental phase characterized by major organ formation?

The developmental phase characterized by major organ formation is embryonic development. This phase occurs from approximately the third to the eighth week of gestation and is critical for the formation of foundational structures in the developing embryo. During this time, the process of organogenesis takes place, where the basic structures of the major organs, such as the heart, lungs, kidneys, and brain, begin to form.

Embryonic development is essential since it lays the groundwork for the rest of the pregnancy and affects the overall health and functionality of the organs as the fetus continues to grow in later stages.

Fetal development, which follows embryonic development, primarily focuses on the growth and maturation of these organs rather than their initial formation. The neonatal period occurs after birth when the newborn's body undergoes further adaptations to life outside the womb. Conception, while the starting point of pregnancy, does not involve organ formation but rather is the initial stage of fertilization and early cellular division.