Pharos-Tribune

Online only

March 5, 2013

Can eyes see outside of the head?

PITTSBURGH — Recently, we have witnessed remarkable, fictional-sounding advancements in science and medicine. There's a guy who can hear color, another with a bionic eye attached to his brain, and a woman fighting back against the debilitating symptoms of multiple sclerosis by placing electrodes on her tongue. But for our next trick, we're going to need a bucket of tadpoles with eyes on their butts and some good old-fashioned alternating current. In other words, things are about to get all kinds of weird.

There's a great deal of wow to unpack here, so let's take it piece by piece. Using embryos from the African clawed frog (Xenopus), scientists at Tufts' Center for Regenerative and Developmental Biology were able to transplant eye primordia — basically, the little nubs of flesh that will eventually grow into an eye — from one tadpole's head to another's posterior, flank or tail. They don't play around with nerve endings or "wiring" or anything like that. They just cut out the cells from the head, slice open a bit of the tail, and jam them in.

As the eyes grow, they send out snaking tendrils of nerve fiber, or axons. We know this because the "tissue donor" tadpoles — a term that makes it sound like they had a choice — were injected with tdTomato, a fluorescent red protein. This allowed the researchers to watch innervation, or nerve growth, as it happened. Of those eye primordia that sent out feelers, nearly half hardwired directly into the spine, while the other half built connections to the nearby stomach. None of the tadpoles grew tdTomato-marked pathways to the brain.

Before they could test the ectopic eyes however, the native ones had to be severed and removed. Otherwise, how would the scientists know which of the tadpole's three eyes was truly seeing? (Note: Severing optical nerves sounds like nasty business, but even these partially-developed tadpoles received anesthesia via fish sedative. Wounds healed completely within 24 hours.)

Text Only | Photo Reprints
Online only
Hyperlocal Search
Premier Guide
Find a business

Walking Fingers
Maps, Menus, Store hours, Coupons, and more...
Premier Guide
Poll

Does Indiana need a statewide water management plan and an administrator to implement it?

Yes
No
Unsure
     View Results
Featured Ads
AP Video
Obama: World Is Appalled by Murder of Journalist Israel, Militants Trade Fire After Talks Fail Pres. George W. Bush Takes Ice Bucket Challenge Pierce Brosnan's Call to Join the Expendables Changes Coming to No-Fly List Raw: IDF Footage Said to Show Airstrikes Police: Ferguson More Peaceful Raw: Aftermath of Airstrike in Gaza Raw: Thousands March on Pakistani Parliament Raw: World's Oldest Man Lives in Japan Fire Crews Tame Yosemite Fire Raw: Police Weapon Drawn Near Protesters, Media Raw: Explosions in Gaza As Airstrikes Resume Charter Schools Alter Post-Katrina Landscape Texas Gov. Perry: Indictment 'a Political Act' US Officials: Video Shows American's Beheading Video Shows Ferguson Cop Months Before Shooting Water Bottles Recalled for Safety Researcher Testing On-Field Concussion Scanners
Parade
Magazine

Click HERE to read all your Parade favorites including Hollywood Wire, Celebrity interviews and photo galleries, Food recipes and cooking tips, Games and lots more.