Bright Eyes

A growing foetus is sheltered from the outside world, but external conditions may still affect it. Only a tiny amount of light manages to get inside the womb, but new evidence suggests this may be essential to ensure eyes develop correctly. Inside each growing eye, a cup-shaped network of blood vessels forms to supply the early retina with oxygen and nutrients. After birth these vessels are no longer needed, so they slowly break down. The left-hand image shows the pattern of vessels (stained blue) in the eye of a healthy eight-day-old mouse. In genetically engineered mice that lack the light-absorbing protein melanopsin (right-hand image) the vessels fail to break down normally post-birth, persisting as a dense, tangled mess. Exactly the same thing happens if a foetus grows in total darkness. This discovery may help to explain certain eye abnormalities, although the influence of light during human pregnancy is still unknown.

Written by Emma Stoye

Emma Stoye

Writer

Cambridge-based Emma works for Research SEA and Asia Research News. She has a degree in biological sciences from Oxford University, and has written, edited and produced material for the Naked Scientists radio show.

• Sujata Rao
• Cincinnati Children’s Hospital Medical Center, USA
• Reprinted by permission from Macmillan Publishers Ltd: Nature Copyright 2013
• Published in Nature 2013