What is the Difference Between Lamellipodia and Filopodia

The main difference between lamellipodia and filopodia is that lamellipodia are cytoskeletal protein projections made up of actin proteins on the leading edge of the cell, whereas filopodia are slender cytoplasmic projections that extend beyond the lamellipodia.

Lamellipodia and filopodia are two types of cytoplasmic projections on the leading edge of mobile cells. Within the lamellipodium, actin ribs are known as microspikes, and when they extend beyond the lamellipodia, they’re known as filopodia.

Key Areas Covered

1. What are Lamellipodia
   • Definition, Characteristics, Importance
2. What are Filopodia
   • Definition, Characteristics, Importance
3. Similarities Between Lamellipodia and Filopodia
   • Outline of Common Features
4. Difference Between Lamellipodia and Filopodia
   • Comparison with Key Differences

Key Terms

Filopodia, Lamellipodia

What are Lamellipodia

Lamellipodia are cytoskeletal actin proteins on the leading edge of a mobile cell. Generally, they contain a quasi, two-dimensional actin mesh, which can propel the whole structure across a substrate. Lamellipodia contain ribs of actin filaments known as microspikes. Some of these microspikes spread beyond the lamellipodium frontier, and are called filopodia. In addition, the primary area of actin incorporation is actin nucleation in the plasma membrane of the cell.

Figure 1: Lamellipodia and Filopodia

Furthermore, lamellipodia occur primarily in all mobile cells. For instance, the keratinocytes of frogs and fish move over the epithelial surface at 10–20 μm / min speed. Moreover, it allows the quick repair of wounds. Therefore, during cell migration, the main function of lamellipodia is to move the cell forward. Exocytosis occurs at the tip of the lamellipodia in migrating cells and actin polymerization extends the lamella forward and thus advances the cell’s front.

What are Filopodia

Filopodia are slender cytoplasmic projections that extend beyond the leading edge of lamellipodia in migrating cells. Therefore, filopodia are the actin ribs that extend beyond the lamellipodia. Normally, filopodia contain microfilaments also known as actin filaments. Actin filaments form cross-links by actin-bundling proteins, fascin, and fimbrin.

Figure 2: Filopodia

Moreover, filopodia have two functions in cell migration. They are the focal adhesion of the cell with the substratum, linking them to the cell surface and the involvement in the sensation of chemotropic cues, resulting in changes in directed locomotion. In addition, filopodia play a key role in cell-cell interactions. During wound healing in vertebrates, growth factors serve as stimulation to the formation of filopodia.   

Similarities Between Lamellipodia and Filopodia

• Lamellipodia and filopodia are two types of projections on the leading edge of the mobile cells.
• They belong to the cell migration tissue.
• Their main function is cell migration.
• Both structures need actin filament assembly.

Difference Between Lamellipodia and Filopodia

Definition

Lamellipodia refers to a flattened extension of a cell, by which it moves over or adheres to a surface, while filopodia refer to a long, slender, tapering pseudopodium, as found in some protozoans and in embryonic cells.

Significance

Lamellipodia are cytoskeletal protein projections made up of actin protein on the leading edge of the cell whereas filopodia are slender cytoplasmic projections that extend beyond the lamellipodia.  

Function

Usually, lamellipodia are involved in the movement of the growth cane while filopodia primarily act as the environmental sensors.   

Conclusion

In brief, lamellipodia and filopodia are two actin protein structures that occur at the leading edge of the migrating cells. Generally, the formation of both lamellipodia and filopodia occurs through the actin nucleation of the plasma membrane. Their main function is to aid in cell migration. However, lamellipodia are cytoskeletal protein projections while filopodia extend further. Lamellipodia involve in cell migration and cell-cell interactions, while filopodia involve in the sensation of chemotropic cues. Hence, the main difference between lamellipodia and filopodia is their structure and function.

References:

1. Lamellipodium. Lamellipodium – an overview | ScienceDirect Topics. (n.d.). Retrieved September 22, 2022.
2. Filopodia. Filopodia – an overview | ScienceDirect Topics. (n.d.). Retrieved September 22, 2022.

Image Courtesy:

1. “GrowthCones” By Chris1387 – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Filopodia” By Lubov Czech, Tatyana Svitkina, and Changsong Yang – Own Work (CC BY 3.5) via Commons Wikimedia