Summary:
- Embryonic Development (Weeks 4–8) Most organs develop in the embryo during weeks 4 through 8.
- An embryo forms three distinct cell layers, and each layer develops into different types of cells and organs.
- If the embryo is exposed to toxins during this period, the effects are likely to be very damaging.
- Can you explain why?
- (Note: the drawings of the embryos are not to scale.)
- The embryo is about 30 millimeters (just over 1 inch) in length by the eighth week of development.