From: Associated Press
Published August 15, 2007 05:45 PM

Bright Lights May Damage Embryos

The kind of light commonly used in fertility clinics could damage the development of human and other animal embryos in research, according to research findings conducted by a team from Hawaii and Japan.

Sunlight and cool-white fluorescent lights caused the most damage to mice embryos in the study, even when exposure was limited to a few minutes, said Ryuzo Yanagimachi, a retired University of Hawaii researcher known for his expertise in reproductive biology.

Cool-white fluorescents, which are blue-white in appearance, are commonly used in office environments.

Warm-white lights, which are yellow-white in color and popular in residential settings, resulted in "far more" eggs developing into babies, Yanagimachi said.

"We found that warm-white light is less damaging," Yanagimachi said.


Watch how a pregnant robot helps train medical students.

The findings were published in the Aug. 13 issue of Proceedings of the National Academy of Sciences of the United States of America.

Although this study focused on mouse embryo development, it is likely human embryos also can be affected by light, said Yanagimachi, who researched with Manami Takenaka and Toshitaka Horiuchi of the Prefectural University of Hiroshima.

He suggested that labs working with human or animal embryos should improve their techniques so that exposure to light is minimized during egg collection and insemination, and while fertilized eggs are examined before being transferred back into the womb.

"People do not pay much attention to light as a negative environmental factor," he said.

Exposure of mice embryos to direct sunlight, even for just 10 seconds, caused the most damage, according to the study.



Light exposure places stress on the embryo, which responds by producing increased levels of radical oxygen that are toxic to cell structures, Yanagimachi said.

Even before his study, Yanagimachi said he preferred warm-white light for his work, which has including cloning a mouse in 1998 and creating three generations of mice from the first clone.

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