Difference Between Cilia and Stereocilia

Cilia vs Stereocilia

Cilia (cilium in the singular) are fine hair-like projections from eukaryotic cells. The respiratory tract has numerous cilia that sweep in harmony to sweep away fluids and other foreign particles. Single-celled organisms also have these projections, which help them with locomotion. The rhythmical movement of cilia helps them move from place to place. The word cilium comes from Latin and refers to the edge of the eyelids and so to eyelashes.

A cilium can be either of two types ‘“ motile or non-motile. Motile cilia continuously move in one direction, which results in movement of cells, fluids, mucus, etc. Non-motile cilia, on the other hand, normally function as sensory organelles.

Cilia in human (and animal) bodies protect individuals from germs in the lungs by propelling microbes and mucus out of the airways. There are also cilia responsible for moving ova down the fallopian tube in females.

Stereocilia are different from cilia, even though they have a similar name. In fact, they are more closely related to microvilli, and some may well consider stereocilia to be a variant of microvilli. They indeed share some features of microvilli. However, stereocilia’s distinctive characteristics are their length and lack of motility. Stereocilia are basically apical modifications of the cell.

Stereocilia are mechanosensing organelles of hair cells, which respond to fluid motion, or changes in fluid pressure in numerous types of animals for various functions, primarily hearing. The length of a stereocilium is about 5mm. Pressure and mechanical stimuli are turned by the stereocilia into electric messages, or neuronal signals, through the microvilli that make up the stereocilia rods.

With their function as mechanoelectrical transducers, their design and assembly is vital. They are arranged in bundles of about 30 to 300, and are usually lined up in rows based on increasing height, much like a staircase. Their shafts contain numerous fine longitudinal actin filaments. In the human body stereocilia are found on the cochlea in the inner ear, ductus deferens, and epididymis.

Summary:

1. Cilia can be motile or non-motile, whereas stereocilia are characterized by their lack of motility.

2. Stereocilia are actually more associated with microvilli, than cilia.

3. (Motile) Cilia’s function are to move cells, or propel objects, while steriocilia are mechanosensing organelles.

4. In the human body cilia are particularly found in the respiratory passages as a defense against unwanted foreign germs and objects, while stereocilia are found on the cochlea in the inner ear, ductus deferens, and epididymis.

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