Friday, February 11, 2011

Eye Disection

Cow Eye Dissection Lab Report

In this experiment we delved into a cow’s eye to explore and better understand its structures and inner workings. We first examined the eye from the outside. It was oval, slightly wrinkled, and just a little bit bigger than a golf ball about 3.5 to 4 cm in diameter. It was covered in a small amount of fat and brown muscle tissue. The first step that we took to begin our journey into the cow’s eye was the removal of the fat and muscle tissue that was still connected to the outside of the eye. We proceeded doing this with a scalpel and scissors to cut the excess fat off. After we had removed the fat we then used a scalpel to make an incision around the center of the eye, cutting the eye completely in half to make a front and a back half. In the center of the eye was the humour which was clear with a light grayish tinge. It felt like lumpy jelly in the hand. Looking at the front half of the eye, there was a whitish half globe that contained the lens. This whitish part that held the lens was the cornea. It was very soft and stretchy, measuring 2mm thick. It felt like it was made of rubber to the touch. The cornea made a crunchy sound when we cut into it. The lens was a very hard pink colored opaque oval measuring 18mm in diameter and 12mm thick. We cut into it with the scalpel to reveal that the lens itself could be peeled apart like an onion. However, it was not flaky like an onion. It was more like an onion made of string cheese. An interesting thing happened when we peeled more layers off. The more that we peeled the clearer the lens got, until finally it was a small almost completely clear marble. We then proceeded to take out the iris and inspect it. The outside portion of the iris was a dark brown/black with a ring around the pupil that was a lighter brown with striations running from the outer perimeter of the eye in towards the iris. The back side of the iris, which faces the inside of the eye was all black save for the slit that is the pupil. The pupil measured 7mm wide and 12mm tall. Turning our attention to the back half of the eye we looked at the retina. The retina was black around the edges but towards the middle it turned to a shiny blue green. It very closely resembled the color and shine of an opal. In the middle of the shiny part of the retina towards the bottom was the optic nerve sticking through. It was pink and measured 4 mm in diameter. Looking at the outer side of the back half of the eye, we could see where the optic nerve exited the eye. It was a white colored knob with some brown muscle tissue surrounding it. This was the extent of our experiment. We properly disposed of the eye after completion.

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