光能促进胎儿眼睛发育

Light passing through the body and into the womb has an important role in the developing eye, US researchers have discovered.

美国研究人员发现，光穿透人体进入子宫对于胎儿眼睛发育有重要作用。

A study, published in the journal Nature, showed that mice spending pregnancy in complete darkness had babies with altered eye development.

It indicated tiny quantities of light were needed to control blood vessel growth in the eye.

The researchers hope the findings will aid understanding of eye disorders.

Light or dark?

If you could journey inside a mouse or a person, there would not be enough light to see. However, tiny quantities of light do pass through the body. 

This effect has already been used to film an infection spreading through the body.

Now scientists - at the University of California, San Francisco, and Cincinnati Children's Hospital Medical Center - believe that body-penetrating light can alter the development of the eye, at least in mice. 

Normally, a network of blood vessels known as the hyaloid vasculature is formed to help nourish the retina（视网膜） as it is constructed. 

However, the blood vessels would disrupt sight if they remained, so they are later removed - like scaffolding from a finished building.

The researchers said this did not happen when the pregnancy was spent in total darkness.

The critical period was around 16 days - which is very late in mouse gestation（酝酿，怀孕）, but corresponds to the first trimester in people. 

"It's not something subtle here, it's a major effect on the way the retina develops that requires light going through the body," said Prof Richard Lang, from Cincinnati Children's Hospital.

He said it was a "huge surprise" that this was happening.