Last day of class: Experiment of oral mucosa epithelial cells

Alumno fotografiando su muestra

Hoy en nuestro último día de clase de Biología de 1º ESO B hemos realizado la práctica en el laboratorio de "observación de células del epitelo de la mucosa bucal (Oral mucosa epithelial cells).

Equipment and Supplies

Soap and Water
Microscope Slides
Dropper Bottle of dH₂O
Dropper Bottle of 0.3% Methylene Blue
Bunsen Burner, Striker
Paper Towel

Preparation of Slide and Fingernail:

Wash Slide

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

Clean Finger Nail 

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

Collecting Cheek Cells

GENTLY scrap the inside of your cheek to pick up some of the cells. Do NOT scrape chunks. 

Expressing the cells

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 on slide.

Fix the Smear

Fix Specimen on Slide

Pass the slide through the flame several times to fix the smear.

Stain the Smear

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

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

Flame again briefly to dry slide.

Examine Under Microscope

Buccal smear

Examine first with the 4x objective, scanning the entire field to find a well-distributed region. Avoid regions 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.

Clean Up

Washed Slides