Buccal Smear

Buccal Smear Lab

The cells which line the inside of your cheeks are classified as a stratified squamous epitheliumtissue and are the surface of a mucous membrane. These flat, scale-like buccal cells (pronounced “buckle”) are shed constantly as the tissue is renewed. By gently scraping the inside of your cheek, these cells can be harvested, and when smeared and stained, may be used to illustrate a number of important biological phenomena including cell and tissue structure, oral bacterial floraand morphology, etc. This tissue is non-keratinized and therefore the surfacecells are living and still possess their nuclei, in contrast with shed epidermalcells. See DiFiore’s Atlas of Histology, 9th Ed, pp 326&327 for similar tissue found lining the vagina. (Note that the keratinized surfacecells of the epidermis have no nucleus.) Here is a labeled image of a buccal smear stained with methylene blue.

Compare the following steps with those in the Bact. Smear and Staining Protocol.

Equipment and Supplies

Soap and Water
Microscope Slides
Dropper Bottle of dH2O
Dropper Bottle of 0.3% Methylene Blue
Toothpicks (optional)
Bunsen Burner or Alcohol Lamp, Striker
Bibulous Paper or Paper Towel

Preparation of Slide and Fingernail:

Wash Slide
Wash Slide


Clean a microscope slide well with soap & water, dry with a non-linty paper towel.



Clean Finger Nail
Clean Finger Nail


Cleanse very thoroughly under the nail of your index finger.



Add Small Drop of Water
Add Small Drop of Water


Place a small drop of dH 20 in the center of the very clean slide.



Harvest the Cells, Prepare the Smear:

Collecting Cheek Cells with Finger
Collecting Cheek Cells

GENTLY scrap the inside ofyour cheek to pick up some of the shed stratifiedsquamous cells. Do NOT scrape chunks. A toothpick may be used if you have no fingernails. Gentle scraping is the watchword, there should be no discomfort.


Express the cheek cells from the fingernail
Expressing the cells





Press Cells onto Slide
Press Cells onto Slide


Express the material from under your nail by pressing with your thumb, and press the material into the drop of water on the slide, mix and spread the material around to the size of a dime.


Spread Material on Slide dime sized
Spread Material on Slide





Fix the Smear

Fix Specimen on Slide
Fix Specimen on Slide


Pass the slide through the flame several times to fix the smear. Do NOT heat the slide above a temp which is comfortable. You are merely “gluing” the smear to the slide.

Stain the Smear

Add Methylene Blue to Slide
Add Methylene Blue

Place a drop of 0.3% methylene blue on the specimen. Let sit for 1 minute.



Rinse off Slide
Rinse off Slide

Rinse off the excess stain with tap water. (Do not splash on your white shirt!)



Blot Dry Slide
Blot Dry Slide

Blot dry with an non-linty paper towel or bibulous paper. Do not rub.



Blot Dry Slide
Blot Dry Slide




Dry Slide with burner
Dry Slide

Flame again briefly to dry slide.



Examine Under Microscope

Buccal Smear
Buccal Smear

Examine first with the 4x objective, scanning the entire field to find a well-distributed region. Avoidregions where cells may be piled up to thickly . Then view with the 10x and 40x objectives, illustrating the view at both powers. Note 1) the nucleus, 2) nucleolus, 3) cell boundary and 4) the variety of bacteria colonizing the surface of the cells.
For Microbiology only: you will be instructed on oil immersion use , then illustrate bacterial morphologies with the 100x oil immersion objective.

Clean Up

Washed Slides
Washed Slides

When finished, scrub the slide well in hot soapy water, rinse well and drain dry in a plastic test tube holder.

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