Answer
If the actin molecules in a cultured skin cell have been randomly labeled such that 1 in 10,000 molecules carries a fluorescent marker and the microscope is sensitive enough to detect single fluorescent molecules, then one would expect to see a diffuse pattern of fluorescence in the lamellipodium of the cell.
Work Step by Step
The thin, sheet-like extension at the leading edge of a migrating cell known as the lamellipodium is made up primarily of a dense network of actin filaments. Only a small percentage of actin filaments will have fluorescently tagged actin monomers due to the random labeling of actin molecules, and the likelihood that any individual filament will contain a labeled monomer is relatively low (1 in 10,000).
As a result, the fluorescent signal in the lamellipodium is probably fairly diffuse and sparse, with sporadic bright spots that represent areas where several tagged actin monomers are close together. Moreover, if none of the actin filaments in a particular region of the lamellipodium contain tagged monomers, that region may not show any fluorescence signal at all.
The distribution of actin filaments within the cell's leading edge may be inferred from the fluorescent signal in the lamellipodium of a cultivated skin cell with a labeling density of 1 in 10,000, however it would be relatively faint and challenging to detect.
