Researchers from Virginia Tech; George-August University in
Gottingen, Germany; and the Jackson Laboratory in Bar Harbor, Maine, have
discovered how “check valves” in wood cells control sap flow and protect trees
when they are injured.
A powerful new type of microscope, the 4Pi, has allowed
scientists to see nanostructures inside of microscopic structures known as
bordered pits within wood fiber cells. Previously, wood had to be dried, coated
with carbon, and put under a high vacuum to be studied at the nanolevel. But
the 4Pi, combined with an optical imaging technique called confocal laser
scanning microscopy, makes it possible to see the wood cells in a more natural
state, which has led to some interesting discoveries.