Thursday, March 14, 2013

[Penn]WikiHow: How to Dissect an Eye

WE DISSECT EYES IN BRAIN AND BEHAVIOR!!! We also dissect brains, but I’m not sure if there are rules against taking pictures of them, whereas I’m pretty sure HIPAA doesn’t apply to cows’ eyes, so it seemed safer to skip the brains and go with the eyes for posting pictures on the Internet. I also didn’t want to get any of my camera-containing devices dripping in formaldehyde, since the brains are preserved.

Here’s how to dissect a cow’s eye in five easy steps, learning team-style:

Warning: This post is full of potentially graphic pictures.
Disclaimer/anti-warning: However, they were taken with my silly-phone (i.e., not smartphone), since I forgot to charge my iPad that day, so they might actually just be too blurry to see.
Plug for Penn, since it’s getting to be recruitment time: Every student gets an iPad! We take notes on them, instead of lugging huge stacks of paper around.
  1. Three eyes per learning team magically appear in the first-floor Stemmler lab rooms.
    Eyes in a bowl
  2. Find the optic nerve and the extra-ocular muscles (muscles around the eye that control eye movement), and cut off the muscles.
    Cleaning an eye
  3. Cut away the front part of the eye. Now you can see the lens (that round blob in the middle), and the vitreous humor behind it. The retina, which contains the photoreceptors that allow us to see, is in the wall around the vitreous humor.
    Inside of eye
  4. Play with the vitreous humor. It’s surprisingly jello-like—on a scale of 1 to 10 where 1 is water and 10 is jello, I’d probably give it a 6.5. If you look through the vitreous at the lens from the other side, you can see a shape exactly like the Mercedes-Benz logo on the back of the lens. Nature’s form of product placement?
  5. Look at the rest of the eye, without the vitreous humor. It’s blue in cows, which helps collect light that isn’t absorbed by the photoreceptors the first time around. That’s why they can see better in the dark than we can. However, it also means that their vision is kind of blurry. (Wikipedia has a better picture)

Ta-da! Basically, Brain and Behavior is super cool.