FIVE BIG QUESTIONS: Embryos use a ruler, of sorts, so they can create the right structures at the right spots from head to tail.
FIVE BIG QUESTIONS: If events weren’t properly timed, pandemonium would ensue. Researchers are ferreting out the internal clocks that control developmental sequence and scheduling.
FIVE BIG QUESTIONS: Research has yielded a parts list of the genes and cell types involved in development. Now it’s time for the computationally intensive task of figuring out how they interact to form a living being.
FIVE BIG QUESTIONS: Some cells seem to know what to do. Others apparently take their cues from outside. But really, “We don’t get it.”
FIVE BIG QUESTIONS: Early in development, an embryo must “break symmetry” to position organs and other parts correctly.