Cheek cells are a common and easily accessible human cell, frequently studied in introductory biology. Found lining the inner surface of the mouth (buccal cavity), their accessibility and simple collection methods make them ideal for observing human cells and understanding basic cellular concepts.
Their Classification and Location
Cheek cells are classified as stratified squamous epithelial cells. They form the outermost layer of the oral mucosa, the mucous membrane lining the mouth. This oral epithelium serves as a primary barrier, defending against mechanical injury, microbial invasion, and chemical irritants from the external environment.
These cells are arranged in multiple layers, contributing to their durability and protective capacity. These cells are constantly shed and replenished, with new cells dividing roughly every 24 hours to maintain the integrity of this vital protective lining. This continuous regeneration ensures consistent protection for the underlying tissues.
Appearance and Role
When observed through a microscope, cheek cells typically appear as flat, irregular, or polygonal shapes, resembling thin plates or tiles. These are eukaryotic cells, with a visible, often centrally located, round or oval nucleus. The nucleus becomes particularly distinct when the cells are treated with a stain like methylene blue. Surrounding the nucleus is the cytoplasm, which fills the cell, and a thin cell membrane encloses the entire structure.
The primary role of these cells is to form a protective lining for the oral cavity. This lining acts as a physical shield, defending against constant friction and abrasion from food during mastication and speech. The cells also prevent the invasion of pathogens and foreign particles into deeper tissues. Additionally, cheek cells secrete mucin, a component of mucus, which combines with saliva to maintain a moist oral environment, facilitating swallowing and initiating digestion.
How They Are Studied
Cheek cells are a popular subject for study due to their accessibility and clear visibility under a light microscope. Their collection is simple and safe, typically involving a gentle scraping of the inside of the cheek with a sterile cotton swab or toothpick. This method yields sufficient cells for observation without causing discomfort.
For microscopic examination, collected cells are smeared onto a clean slide. A drop of water or a staining solution, such as methylene blue, is added to enhance visibility, particularly highlighting the nucleus. A coverslip is carefully placed over the sample, preparing it for observation. This allows direct exploration of human cellular characteristics.