Friday, May 11, 2012

Cow Eye Dissection

*Eliza noted that not everyone might want to look at these photos of cows' eyes. There's your warning! 

We had an awesome day of curiosity (otherwise known as science!!) on Monday. We dissected cows' eyes!! My memory of dissecting is from high school, with mixed feelings of intense curiosity and an equally intense desire to flee the disgusting smell and vapors that made my eyes sting.  The solution to this, I discovered, is to perform the dissection outside on a picnic table, under the shade of a tree. Perfect.  (These eyes were also super-rinsed, leaving them with significantly less smell than I remember.)

Jen, in teacher mode
We read about each bit as we followed our dissection guide.  When we had cut away the muscle and tissue to find the optic nerve, we were talking about this being the conduit for messages to the brain, and Ani kept exclaiming, "It's doing it now! What you're talking about is happening now, while I'm looking at this eye!!" I love her wonder and grasp of the present.  She in particular loves learning about the body.
Osha cutting away tissue to get a better look
Bisecting the eye
looking for the humor...ha, get it?
vitreous humor
the lens

the inside of the iris; the radial muscles are visible on the left of the photo
The retinal tissue (the white stuff), attached to the optic nerve; the iridescent tapetum lucidum

It looks like abalone; so beautiful.
The tapetum lucidum (latin for bright tapestry according to wikipedia) was a surprise to me; isn't nature amazingly beautiful? The purpose this part serves is to reflect light onto the retina to enable better night vision.  Think of the shine of a cat's eyes at night as they reflect light back to you; that's coming from its tapetum lucidum.  Now, why a cow needs that, I'm not so sure. It's not something humans have, but in other aspects the cow's eye is very similar to our own.

The last one at the table, intent on examining and feeling every part
Eliza's assessment? Sweet. But you have to not mind touching yucky stuff...


Kerry said...

Euwwwwww! Fascinating and gross all at once. I just realized that the "clay needles" sold in ceramics shops to cut clay...they're the same awful little instruments I used in biology class to scramble frog brains. So devious and genius to sell the same things to artists! oh well, this was really a cool lesson for the girls. maybe Ani will be a surgeon some day.

Stephanie said...

I'm fascinated at appalled, myself. The formaldehyde has been exiled, I guess, but I still don't know how I'd do.
The scientist me says "Cool!", and the tactile me says "I dunno 'bout that." :)