What Will Happen by the End of the Eighth Week

Question

What will happen by the end of the eighth week of development?  
A) Limbs form, and paddles at their ends are sculpted into digits.
B) The umbilical cord and the circulatory system develop.
C) All of the organ systems will be formed, and apoptosis has eliminated the tail.
D) The fetal heartbeat can be heard clearly through a stethoscope positioned on the mother's abdomen.
E) The fetus has begun not only to detect sounds but also to remember some of them.

Accepted Answer

By the end of the eighth week of development, all of the organ systems will be formed, and apoptosis (programmed cell death) has eliminated the tail. Limbs form and paddles at their ends are sculpted into digits by the end of the fifth week. The umbilical cord and the circulatory system develop by the end of the fourth week. The fetal heartbeat can be heard clearly through a stethoscope positioned on the mother's abdomen by the end of the tenth week. While the fetus is capable of detecting sounds by the end of the eighth week, there is no evidence to suggest that it can remember them at this early stage of development.