Development occurs from about week two through which week in gestation?

Development in gestation is a crucial aspect of prenatal growth, and it typically encompasses various stages marked by significant changes in the embryo. This developmental process begins around the second week after conception when the embryo becomes implanted in the uterine wall.

By the end of the eighth week, most of the major organ systems are formed in a process often referred to as organogenesis. This is a critical period of development, during which the foundations for the future functioning of the body's systems are established. Therefore, it is at this point, around the end of the eighth week, that development can be considered to have progressed through the early stages and into a more mature phase.

The development does not traditionally extend to the fifth week or sixth week alone, as significant changes continue to occur through the end of the eighth week. By the tenth week, the embryo transitions into a fetus, marking the end of the embryonic stage, but the core development processes are strongly centered around that eighth week timeframe. Thus, identifying the eighth week as the conclusion of this developmental phase aligns with the established biological understanding of embryological growth.