What is the correct order of events as a pancake-shaped cell walks in culture?

The order of cell movement involves precise processes that allow for effective locomotion. In this context, filopodia are slender, finger-like projections that extend from the cell membrane, playing a critical role in sensing the environment and providing traction during movement. When a pancake-shaped cell begins to move, it first extends filopodia to probe the substrate for adhesion and signaling cues.

Following the establishment of a stable contact through filopodia, the cell generates lamellipodia, which are broader, sheet-like protrusions that facilitate the expansion of the cell's surface area as it moves forward. These structures are crucial for generating the necessary leading edge that pushes the cell in a particular direction.

"Cell muscle," which likely refers to the contractile elements that can pull on the rear of the cell, comes into play as the cell starts to retract its old position while moving forward. This retraction is supported by retraction fibers, which help to pull the body of the cell toward the leading edge after lamellipodia have anchored to the new substrate, thus completing the propulsion mechanism of the cell.

This sequence establishes a functional pathway by which the cell can effectively migrate across a surface. Each component plays a specific role in ensuring that the process of cell motility