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Special Report: Building Bodies

Bent into shape: The rules of tree form

How do trees find their sense of direction as they grow? Researchers are getting to the root — and the branches — of how the grandest of plants develop.

How do body parts grow to their right sizes?

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.”

How do bodies map out left and right?

FIVE BIG QUESTIONS: Early in development, an embryo must “break symmetry” to position organs and other parts correctly.

How do bodies position arms, legs, wings and organs?

FIVE BIG QUESTIONS: Embryos use a ruler, of sorts, so they can create the right structures at the right spots from head to tail.

How does the embryo make all its parts at just the right moments?

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.

Will we ever fully know how a body gets built?

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. 

Regeneration: The amphibian’s opus

Certain salamanders can regrow lost body parts. How do they do it? And could people someday do the same?

Plumbing 101: Building the body’s tubes and branches

Lungs, blood vessels, kidneys and more: Our bodies are full of branching pipes. Their development follows a handful of basic principles.

Growing a body, one tiny tug at a time

For decades, genetics and biochemistry have formed the bedrock of developmental biology. But it turns out that physical forces — the way cells push, pull and squeeze each other — play a huge role, too.