Step-By-Step: Dissecting A Cow Eye

sclera cornea 1. Examine the outside of the eye. See how many parts of the eye you can identify. You should be able to find the white (sclera) and the clear covering over the front of the eye (cornea). You should also identify the fat and muscle surrounding the eye.

2. Cut the eye in half. Cut slightly toward the posterior of the eye to avoid cutting the lens.

scleravitreous humor aqueous humor vitreous humor As you cut through the sclera, the vitreous humor and aqueous humor will begin to come out of the eye. Let it come out slowly. Sometimes the retina will detach and begin to come out with the vitreous humor. If this happens, reduce the pressure of your fingers on the outside of the eye. Cut carefully and the retina may remain on the back of the eye.

lens 3. View of the anterior (front) half of the eye. If you have cut the eye carefully, the lens will still be intact in the anterior half of the eye.

The lens lensvitreous humor vitreous humor iris 4. The lens. If you tip the front half of the eye over, the lens and vitreous humor will usually fall out. The stiff lens will be in the center of a disk of jelly-like material (vitreous humor). The iris should be easily visible in the remains of the anterior half of the eye.

lens. lens lens 5. Magnification of the lens. If you remove the lens, you can observe its ability to magnify. Hold the lens up and look through it. If it is too slippery, pat it dry and try again.

6. View of the posterior (back) half of the eye. retina In this image, the retina is still spread over the rear of the eye. retina In this image, the retina is the pinkish mass detached from the rear of the eye. retina

tapetum The shiny blue-green material is the tapetum.

retina blind spot optic nerve 7. Find the spot where the retina is attached to the back of the eye. It is called the blind spot. This is where all the nerves go out the back of the eye, forming the optic nerve.

optic nerve. 8. Return your attention to the outside of the eye. Locate the optic nerve.

9. Once the dissection is complete, properly dispose of the remains, clean your work area, and wash your hands thoroughly.

Terms To Learn aqueous humoraqueous humor blind spotblind spot ciliary bodyciliary body conescones corneacornea irisiris lenslens optic nerveoptic nerve retinaretina rodsrods sclerasclera tapetumtapetum vitreous humorvitreous humor

Terms To Know Aqueous humor-Aqueous humor- a clear fluid that helps the cornea keep its rounded shape. Blind spot-Blind spot-The area where the optic nerve leaves the retina. Each eye has a blind spot where there are not photoreceptor cells (rods and cones). Ciliary body-Ciliary body-Muscles that control the shape of the lens for near and far vision.

Cones-Cones- One type of photoreceptor cells in the retina. They are responsible for daylight and color vision. Cornea-Cornea-A clear, tough covering over the iris and the pupil that helps protect the eye and begins focusing the light. Iris-Iris-A muscle that controls the amount of light that enters the eye. It is suspended between the cornea and the lens.

Lens-Lens-A clear, flexible structure that adjusts the eye’s focus, allowing us to see objects both near and far. Optic nerveOptic nerve-The bundle of nerve fibers that carry information from the retina to the brain. Retina-Retina-The layer of light-sensitive cells lining the inner eyeball. It detects images focused on the back of the eye by the lens and the cornea. The retina is connected to the brain by the optic nerve.

Rods-Rods-One type of photoreceptor cells in the retina. They respond to dim light. ScleraSclera-The thick, tough, white outer covering of the eyeball. Tapetum-Tapetum-The colorful, shiny material located behind the retina. Found in animals that have good night vision, it reflects light back through the retina. Vitreous humorVitreous humor-The thick, clear jelly that helps give the eyeball its shape.

1. Cornea 7. Ciliary body Retina 3. Optic nerve 9. Tapetum 4. Iris 10. Cones and rods 5. Pupil 11. Lens 6. Sclera 12. Vitreous humor