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

Should e-cigarette marketing be regulated like tobacco?

Yes
No
Unsure
     View Results
Featured Ads
AP Video
Tributes Mark Boston Bombing Anniversary Raw: Kan. Shooting Suspect Faces Judge US Supports Ukraine's Efforts to Calm Tensions Suspect in Kansas Shootings Faces Murder Charges Ukraine: Military Recaptures Eastern Airport Raw: Storm Topples RVs Near Miss. Gulf Coast NASA Showcases Lunar Eclipse Pistorius Cries During Final Cross-Examination The Boston Marathon Bombing: One Year Later Michael Phelps Set to Come Out of Retirement First Women Move to Army Platoon Artillery Jobs Sex Offenders Charged in Serial Killings Police: Woman Stored Dead Babies in Garage OC Serial Murder Suspects May Have More Victims Family: 2 Shot in Head at Kan. Jewish Center Raw: Horse Jumping Inspires 'Bunny Hop' After Attack, Officials Kill 5 Bears in Florida Popular Science Honors Year's Top Inventions ND Oil Boom Attracting Drug Traffickers
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.