Difference Between Cilia Stereocilia and Microvilli

The key difference between cilia stereocilia and microvilli is that cilia are tiny hair-like structures composed of microtubules while stereocilia are bundles of hair-like projections composed of actin filaments and microvilli are folds of cell membranes composed of actin filaments.

Cilia, stereocilia and microvilli may appear as similar structures when observed from the outside. But they are structurally and functionally different from each other. They are hair-like structures which are microscopic. Moreover, they are protein fibers that extend outward from the cells.

CONTENTS

1. Overview and Key Difference
2. What is Cilia 
3. What is Stereocilia 
4. What is Microvilli
5. Similarities Between Cilia Stereocilia and Microvilli
6. Side by Side Comparison – Cilia Stereocilia vs Microvilli in Tabular Form
7. Summary

What are Cilia?

Cilia are shorter and tiny hair-like structures present on certain cell surfaces. Generally, cilia have a uniform length. They are composed of hollow tubes known as microtubules. Cilia are mainly motile. They show rhythmic, sweeping motion in order to move materials in one direction parallel to the epithelial surface. There are three parts of a cilium. They are the basal body, the transition zone and the axoneme. The basal body is the base of the cilium.

There are some non-motile cilia as well. Motile cilia show 9+2 microtubule arrangement while non-motile cilia have 9+0 arrangement. Cilia line the epithelium of our respiratory tract. In respiratory passages, cilia sweep out mucus, dust, and dirt, helping us to breathe easier. Moreover, cilia are present in reproductive tracts, especially in the male reproductive system.

What are Stereocilia?

Stereocilia are hair-like protrusions composed of actin-based protein filaments. In fact, they are bundles of hair-like projections. They are longer than cilia. Unlike cilia, stereocilia are non-motile. Similar to microvilli, stereocilia are absorptive.

There are stereocilia in the inner ear in auditory and vestibular sensory cells.  In there, stereocilia serve as sensory transducers. Moreover, stereocilia are present in the male reproductive tract. There, stereocili facilitate absorption on the epididymis and ductus deferens.

What are Microvilli?

Microvilli are folds of the cell membrane of certain cells, especially in cells where absorption and secretion take place. They extend outward from the surface of the cell. Similar to cilia, they have a hair-like appearance. In fact, they are protein fibers. They contain actin filaments.

Microvilli are specialized for absorption and secretion. Hence, they are mainly present in the digestive tract and kidneys. Our small intestine has a lot of microvilli.  Microvilli increase the surface area of the cell membrane for absorption. Therefore, the efficiency of the absorption process enhances. Unlike cilia, microvilli do not move. Moreover, microvilli are shorter than cilia.

What are the Similarities Between Cilia Stereocilia and Microvilli?

• Cilia, stereocilia and microvilli are hair-like structures found in the human body.
• They are microscopic structures that consist of protein fibers.
• They extend outward from the cell.

What is the Difference Between Cilia Stereocilia and Microvilli?

Cilia are microtubule-based hair-like structures that project from the surface of cells. Stereocilia are bundles of actin-based filaments while microvilli are folds of cell membranes of absorptive and secretory cells. So, this is the key difference between cilia stereocilia and microvilli. Cilia are mainly motile while stereocilia and microvilli are non-motile. Moreover, stereocilia and microvilli are absorptive while cilia are not.

The below infographic shows more descriptions of the difference between cilia stereocilia and microvilli.

Summary – Cilia Stereocilia vs Microvilli

Cilia, stereocilia and microvilli are three types of hair-like microscopic structures found in the human body. Cilia are motile while stereocilia and microvilli are non-motile. Moreover, stereocilia and microvilli are absorptive while cilia are not. Cilia are composed of microtubules while stereocilia and microvilli are composed of actin filaments. Thus, this summarizes the difference between cilia stereocilia and microvilli.

Reference:

1. “Stereocilia (Inner Ear)”. En.Wikipedia.Org, 2020, Available here.
2. “Cilium”. Biology Dictionary, 2020, Available here.
3. “Microvilli: Definition & Function.” Study.Com, 2020, Available here.

Image Courtesy:

1. “Blausen 0750 PseudostratifiedCiliatedColumnar” Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia
2. “1407 The Hair Cell” By OpenStax –  (CC BY 4.0) via Commons Wikimedia
3. “Villi & microvilli of small intestine” By BallenaBlanca – (CC BY-SA 4.0) via Commons Wikimedia