Cilia- Definition, Structure, Formation, Types, Functions, Examples


Cilia are microscopic structures that protrude from the surface of some eukaryotic cells. They are composed of bundles of protein filaments called microtubules, arranged in a characteristic 9+2 pattern. The microtubules are connected by cross-linking proteins and anchored to the cell membrane by a basal body.

Cilia can be classified into two types based on their function and structure: motile and non-motile. Motile cilia are capable of generating coordinated movements that propel the cell or the surrounding fluid. Non-motile cilia, also known as primary cilia, are usually solitary and act as sensory organelles that detect signals from the environment.

The term `cilia` comes from the Latin word for eyelash, reflecting their resemblance to tiny hairs. However, cilia vary in size, shape, number, and distribution depending on the cell type and function. For example, some cilia are long and slender, while others are short and stubby. Some cells have hundreds or thousands of cilia covering their entire surface, while others have only one or a few cilia localized to a specific region.

Cilia are widely distributed in the living world, from single-celled organisms to multicellular animals. They play important roles in locomotion, feeding, reproduction, development, and disease. In this article, we will explore some of the examples and functions of cilia in different organisms.