What occurs during the embryonic period?

During the embryonic period, which spans from the second to the eighth week of gestation, the most critical and significant growth and development of the embryo occurs. This is the stage when major organs and structures begin to form. Notably, the foundation for the heart, brain, spinal cord, limbs, and other vital systems develops during this time, setting the stage for further growth throughout the pregnancy.

While rapid cell division is indeed a vital part of the overall developmental process and happens during this period, it is not the defining feature of the embryonic stage. Fertilization is an event that occurs prior to the embryonic period, specifically marking the beginning of conception. Additionally, the onset of labor signifies the transition to the final stages of pregnancy and does not pertain to embryonic development at all. Thus, focusing on the development of major organs and structures accurately encapsulates the primary events of the embryonic period.