Stratified tissue, specifically stratified epithelium, is a type of tissue composed of two or more layers of cells. Its primary function is protection, with the number of layers directly correlating to the degree of protection offered. This makes it highly resistant to abrasion. The cells within stratified epithelium can vary significantly in shape and height between layers.
Characteristics of Stratified Epithelium
- Multiple Cell Layers: The defining characteristic is its multi-layered structure, unlike simple epithelium which has only one layer.
- Protective Function: Its main role is shielding underlying tissues from damage, including physical abrasion.
- Varied Cell Shapes: Cell morphology (shape) differs between layers, contributing to its protective capability.
- Location: Found in areas requiring high levels of protection, such as the skin (epidermis), the lining of the esophagus, and parts of the oral mucosa.
Types of Stratified Epithelium
While many sources focus on stratified epithelium, it's important to note that the term "stratified tissue" can, in principle, refer to other tissues beyond epithelium. However, the provided references overwhelmingly focus on stratified epithelium. Examples of stratified epithelium include:
- Stratified squamous epithelium: This is the most common type, found in the epidermis (skin), esophagus, and vagina. It can be keratinized (e.g., skin) or non-keratinized (e.g., esophagus).
- Stratified cuboidal epithelium: Less common, found in ducts of certain glands.
- Stratified columnar epithelium: Also relatively rare, found in parts of the male urethra and some large ducts.
Practical Insights and Examples
- The skin's epidermis, a keratinized stratified squamous epithelium, acts as a robust barrier against environmental threats.
- The non-keratinized stratified squamous epithelium lining the esophagus protects against damage from food passage.
- The thickness and layering of stratified epithelium can vary depending on the location and degree of protection needed.
The references highlight the protective nature of stratified epithelium, its multi-layered structure, and the variability in cell shapes between layers. They also provide examples of its presence in different body locations, emphasizing its crucial role in protecting underlying tissues.
