pylväsepiteeliä

Pylväsepiteeli, also known as columnar epithelium, is a tissue type found in various parts of the body, particularly lining organs and cavities. It is characterized by cells that are significantly taller than they are wide, resembling columns. These cells have a distinct basal nucleus, typically oval-shaped, located towards the base of the cell. The apical surface, facing the lumen or external environment, can exhibit specialized structures such as microvilli or cilia.

Microvilli are finger-like projections that increase the surface area of the cell, crucial for absorption and secretion. This type of epithelium is commonly found lining the small intestine, where it facilitates nutrient absorption. Cilia, on the other hand, are hair-like appendages that beat rhythmically, aiding in the movement of substances. Ciliated columnar epithelium lines the respiratory tract, helping to move mucus and trapped particles away from the lungs, and also the fallopian tubes, propelling the egg towards the uterus.

Pylväsepiteeli can be simple, meaning it consists of a single layer of cells, or stratified, composed of multiple layers. Simple columnar epithelium is involved in absorption and secretion, while stratified columnar epithelium, though less common, provides protection. Goblet cells, a type of specialized columnar cell, are often interspersed within these epithelia, producing mucus. The functions of columnar epithelium are diverse, ranging from nutrient uptake and waste removal to lubrication and mechanical propulsion of materials within the body.