COW EYE DISSECTION

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COW EYE DISSECTION
Use this presentation as your virtual cow eye
dissection, or use it as a guide for your actual
classroom dissection (recommended). If you are
following along at school, please be careful.
Scalpels and razors can cut you as easily as
they cut cow eyes. You can order cow's eyes at a
butcher shop or purchase them directly from a
slaughterhouse. Try to get eyes with the muscles
and fat still attached. If possible pick up the
cow's eyes the day of the dissection, eyes are
easier to cut when they are fresh.
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MATERIALS NEEDED
-One cow's eye for every two participants.-One
single-edged razor blade or scalpel -Scissors
(optional)-Wax Paper and Paper Towels-Plastic
garbage bag
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STEP 1 EXAMINE EYE
Examine the outside of the eye. See how many
parts of the eye you can identify. You should be
able to find the whites (or sclera)
and the clear covering over the front
of the eye (the cornea). You
should also be able to identify the
fat and muscle surronding the eye.
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STEP 2 FIRST INCISION
Make the first incision where the sclera meets
the cornea. Cut until the aqueous humor is
released.
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STEP 3 CORNEA
Rotate the eye and cut around the cornea. Be
careful not to cut too deep or you may cut the
lens. As the cornea starts to cut free, hold
the cornea in the center and make the last
cuts around it.
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STEP 4 CORNEA
Once you have removed the cornea, place it on
the board (or cutting surface) and cut it with
your scalpel or razor.
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STEP 5 IRIS
With the cornea removed, the next step is to
pull out the iris. Place one finger in the
center of the eye. Find the iris and pull it
back. It should come out in one piece.
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STEP 6 SCLERA
It can be a bit tricky to remove the lens with
the vitreous humor attached. It works best if
you cut slits in the sclera. Be careful not to
cut the lens.
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STEP 7 LENS
After enough incisions have been made in the
sclera, you should be able to remove the lens.
Sometimes the vitreous humor will be removed
along with the lens.
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STEP 8 EXAMINE LENS
Hold up the lens and look through it. If the
lens is too slippery, pat it dry and try
again.
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STEP 9 INSIDE OUT
With the vitreous humor now removed, you
should be able to turn the eye inside out.
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STEP 10 RETINA
The thin tissue on the back of the eye is the
retina. Find the spot where the retina is
attached. The shiny blue-green material is the
tapetum.
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STEP 11 OPTIC NERVE
Find the spot where all the retina's nerves
collect. It is called the blind spot. This is
where all the nerves go out the back of the
eye, forming the optic nerve.
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STEP 12 OPTIC NERVE
Return your attention to the outside of the
eye. Locate the optic nerve. To see the
separate fibers that make up the optic nerve,
pinch the nerve with a pair of scissors or with
your fingers.
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STEP 13 CLEAN-UP
Once the dissection is complete, properly dispose
of the remains. They should be wrapped up in
plastic and disposed of the same day. Also, if
you used razor blades, they should be disposed
of properly. (A blade is good for only one or two
dissections.)