Name: ________________________________ Class: ________ Date: _________________

Pig Eye Dissection Materials:

• Gloves • Dissecting tray • Plastic bags (2) • Paper towels (5) • Newspaper • Dissecting scissors • Forceps • Probe (optional) • Pig Eye (not optional)

Procedure:

1. Examine the front of the eye and locate the eye-lid, cornea, and sclera. Examine the back of the eye and find the optic nerve, a white, thick cord attached to the back of the eye.

2. Trim the fat and muscles away from the eye. DO NOT REMOVE THE OPTIC NERVE. The optic nerve carries information from the eye to the brain.

3. Make an incision (cut) in the sclera midway between the cornea and optic

nerve. Cut the sclera all the way around the ball of the eye (See pictures below).

4. Observe the front half of the eye. The vitreous humor, a jellylike material, fills the central cavity (space) inside the eye. It may fall out when you separate the eye. Remove the vitreous humor to see the lens and ciliary muscles. Remove the lens. Note the shape, size, and color of the lens.

5. When the lens is removed, you can see the pupil, which is an opening that allows light to enter the eye.

6. Remove the cornea from the front eye hemisphere. Make a small slit at the boundary between the cornea and sclera. Then insert the scissors into the slip and cut all the way around the cornea to remove it. Carefully observe the front side of the iris and pupil.

7. Now, observe the back half of the eye. The retina lines the back of the eye. Use your probe to lift and pull the retina back from the underlying choroid layer. See the photograph below. Notice that the retina is only firmly attached to the choroid at one place. This region is the blind spot. Here the nerve fibres leave the retina and form the optic nerve, which is directly behind the blind spot.

Post Pig’s Eye Dissection Questions

1. The first structure of the eye that light passes through on its way to the retina is the ________________________.

2. This is the name of the jelly-like fluid that fills the space between the retina and the lens, and makes up 80% of the eye’s volume. ___________________

3. This tough outer covering of the eye is responsible for the “white of the eye”. _____________________

4. The muscles, which control movement of the eye, are called the _______________________________.

5. These cells in the retina respond to bright light and are mainly responsible for the eye’s color sensitivity. _________________________

6. The _____________________ sends visual information from the retina to the brain.

8. This colored circular muscle is responsible for human eye color and adjusts in size to regulate the amount of light entering the eye. ______________________

9. Which are there more of in the human eye, rods or cones? ______________________

10. Both the _______________ and _____________ help to refract, or bend, light as it enters your eye, so that the light can travel to the retina.

11. Are you interested in a career in medicine, as a doctor, nurse, or

some other member of the healthcare community? ______________

12. What was the most interesting part of this dissection? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Post Pig’s Eye Dissection Answer Key

1. Cornea 2. Vitreous Humour 3. Sclera 4. Ciliary Muscles 5. Cones 6. Optic Nerve 7. Iris 8. Rods 9. Cornea and Lens