Wet Mounts – Human Cheek Epithelial Cells

Objective:

Make a wet mount of your cheek epithelial cells and estimate their size.

Materials:

microscope

glass slide

cover slipwater dropper bottle

toothpickmethylene blue stain

Procedure:

  1. Gently scrape the inside lining of your cheek with a toothpick. DO NOT GOUGE THE INSIDE OF YOUR CHEEK!
  2. Gently smear the cheek material off of the toothpick onto the centre of the slide.
  3. ONE PARTNER: Add a small drop of methylene blue stain (specific for animals) on top of the cells and cover with a cover slip using proper wet mount technique.

ONE PARTNER: Place a small drop of water on the cells on the slide and cover with a cover slip using proper wet mount technique.

  1. Observe the unstained specimen first at low, medium and then high power. Adjust the diaphragm to obtain maximum light contrast.
  2. Describe the appearance of unstained specimenin the box below. Include a description of colours, and organelles that could be seen: (2 marks)
  1. Now examine the cheek cells that have been stained with methylene blue
  2. Observe the stained cheek cells under high power. Estimate the number of cells that could fit across the field of view: ______(1 mark)

Calculate the width of one cheek cell. Show your work in the box below. (2 marks)

  1. Make a drawing of two (2) cheek cells at high power, labeling all of its parts as you observe them.(At minimum, you should observe the nucleus, cell membrane, and cytoplasm). Note: each structure only has to be labeled once even thoughtwo cells will be drawn.

Observations:

The labeled drawing should be completed on this handout. The drawing MUST be neat and completed using a pencil, following tall rules for scientific drawings. If you want to show detail, stiple but do not shade. For each diagram, calculate and include the total magnification. Refer to the marking scheme on the bottom of the handout.

Microscope DrawingsName:

Marking Scheme for Diagram:

Possible Mark / Your Score
Title – top of diagram, name of specimen, underlined, printed / 1
Name – top right, complete (full name), printed / 1
Labels –all present and clear, correct spelling
Straight lines, no arrowheads, labels in even column on right side, printed / 5
Diagram – Neat, accurate, clear lines, all erasures are complete, no shading, stipling used for detail, only pencil (including underlining) / 2
Magnification correct, with an “X” written after it. / 1
Total / 10