Module 1

Module 1—The Nervous System

Lab—Dissection of the Eye

 

For this dissection lab, you have the choice of either conducting your own hands-on dissection of a real cow eye or participating in a virtual dissection of an eye. If you wish, you may do both labs.

 

If you choose to do the hands-on lab, you will need access to either a preserved cow eye from a biological supply house or a fresh cow eye from a butcher. A cow eye is typically used for this dissection as its anatomy is very similar to that of the human eye.

 

Review the list of required materials for this lab:

• a preserved cow eye obtained from a biological supply house or a fresh cow eye obtained from a butcher
  
• rubber gloves
  
• safety goggles
  
• a clean dissecting tray or a clean foam tray
  
• sharp scissors with pointed tips
  
• a sharp knife or a scalpel
  
• a bleach solution to be used for cleanup

To complete the hands-on dissection, refer to “Investigation 12.A: Dissection of an Eye” on page 417 of your textbook. You may also find it helpful to view the virtual dissection to help you through the procedure.

 

To view the virtual dissection, watch the "Bio Probe: Cow Eye Dissection" segment of “The Eye: Vision and Perception: A Whole World to See.” You may be required to enter a username and password to be able to view the video. Contact your teacher for this information.

 

As you conduct either dissection, remember that the retina is composed of two important types of photoreceptors called rods and cones. Try to locate the fovea centralis, the small depression in the retina. This area is specialized for sensitivity to colour and acute images as it has a high density of cones. The rods, which are sensitive to light intensity, cover the surrounding area of the retina.

 

The tapetum is a specialized layer located in the choroid. This structure is only typical of animals, such as the cow, that are able to see well in the dark. Try to find the tapetum.

 

The role of the aqueous and vitreous humours should become obvious in the dissection. Think about glaucoma—the disorder that results when the aqueous humour is not successfully drained from the anterior chamber. Be sure to add this disorder to your list.

 

Regardless of which dissection you complete, make sure you create a diagram of the eye that includes the following structures:

 

You may choose to add these to a diagram you have already drawn or develop a new diagram based on the findings of the dissection.

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