Stratified squamous epithelium is a type of
epithelial tissue composed of multiple layers of cells. The cells in the outermost layer are flat and squamous in shape, while the cells in the deeper layers can be more cuboidal or columnar. This type of epithelium is primarily designed to provide protection against mechanical stress, dehydration, and microbial invasion.
Stratified squamous epithelium is commonly found in areas of the body that are subject to significant abrasion. Examples include the
epidermis of the skin, the lining of the
oral cavity,
esophagus, and the
vagina. There are also specialized forms, such as the keratinized stratified squamous epithelium in the skin, which contains
keratin, a tough protective protein.
There are two main types of stratified squamous epithelium:
Keratinized: Found mainly in the skin, this type includes surface layers of dead cells filled with keratin. This layer provides extra protection and waterproofing.
Non-keratinized: Found in moist areas such as the oral cavity, esophagus, and vagina. This type lacks the keratinized layer, making it more suitable for areas where moisture is present.
The primary function of stratified squamous epithelium is
protection. The multiple layers of cells provide a barrier against mechanical injury, pathogens, and water loss. In keratinized types, the keratin layer adds an extra level of protection against environmental factors such as UV radiation and chemical damage.
The structure of stratified squamous epithelium includes several layers:
Basal Layer: This is the deepest layer, consisting of actively dividing cells that give rise to the cells in the upper layers. These cells are more cuboidal or columnar in shape.
Intermediate Layers: These layers consist of cells that are gradually becoming more flattened as they move towards the surface.
Superficial Layer: The outermost layer consists of flat, squamous cells that are eventually shed from the surface.
In
histological sections, stratified squamous epithelium can be identified by its multiple layers of cells and the flat, squamous appearance of the cells at the surface. In keratinized types, you will also observe a layer of anucleate, keratinized cells at the outermost surface. Staining techniques such as
Hematoxylin and Eosin (H&E) are commonly used to highlight these features.
Damage or disease affecting stratified squamous epithelium can lead to various clinical conditions. For example, in the skin, disruptions can lead to
dermatitis or infections. In the oral cavity, conditions like
oral cancer can arise from the epithelial cells. Understanding the histology of this tissue can aid in diagnosing and treating such conditions.
