Question

What type of tissue are cheek cells?

Answer 1

Hint: Mouth is a site where continuous wear and tear is happening. Hence the cells present in the mouth are continuously dividing cells. The cells present in the mouth divide approximately every 24 hours. The upper layer of cells also protects the inner lining.

Complete answer: The cells in the mouth are present in the sheet and all are epithelial cells. These epithelial cells have arisen from all three germ layers i.e., ectoderm, mesoderm, and endoderm. The epithelial cells are surrounded by a basement membrane. The basement membrane has two parts, one part which is in contact with epithelial cells is called the basal lamina. The basal lamina is made up of mucopolysaccharide and it is secreted by epithelial cells itself. Another part is called the reticular lamina. It consists of reticular fibres and secreted by underlying connective tissue. Epithelial cells are arranged adjacent to each other and connected to neighboring cells with the help of cell junctions. Cells present in the mouth or buccal cavity have tight junctions. The inner lining of the buccal cavity consists of epithelial squamous cells. These cells are flattened, polygonal cells, and arranged in a floor like (pavement) manner. The nucleus is present at the centre. More specifically the buccal cavity lined by stratified squamous epithelium, in which only the lowermost layer is in contact with the basement membrane and the uppermost layer is of squamous epithelium. The basal layer is mitotically active and it is known as stratum germinativum. This adds a new layer of cells to the upper surface. Stratum germinativum is followed by stratum granulosum and stratum lucidum. And the uppermost squamous layer is called the stratum corneum.
Hence, the cheek cells were made up of stratified squamous epithelium.

Note: If the keratin is present in the cells of stratum corneum then this epithelium is termed as stratified squamous keratinized epithelium. This keratinized layer is impermeable to water and found in the skin epidermis of amniotes (including reptiles, birds, and mammals).