Too few colonies — sparse, hard to count statistics (Colony Formation Assay)

Question

Accepted Answer

Only a handful of visible colonies per dish; counts are too low to give meaningful statistics. Common causes: 1) Seeding density was too low for this cell line 2) Cell proliferation ability is weak 3) Culture time was insufficient 4) Too much medium changing during culture disturbed colonies Solutions: 1) Increase seeding number (target 50 – 200 colonies per well as the sweet spot) 2) Extend culture time (typically 10 – 14 days) 3) Do NOT change medium during the colony-formation period — let colonies grow undisturbed 4) Check cell state and viability before starting