Before dissociation
- Confirm that the culture state matches the source-specific passage trigger or the validated local baseline.
- Inspect morphology, distribution, debris, medium and any unexpected detached population.
- Prepare labeled vessels, medium, dissociation and neutralization materials before exposing cells.
- Record the evidence supporting the decision to passage.
During dissociation
Use the validated wash and dissociation method for the cell source. Observe detachment rather than relying only on a fixed timer. Excess exposure, forceful pipetting or prolonged single-cell suspension can reduce recovery or change the population.
If a culture consistently requires a different handling condition, document the observation and validate the change instead of silently modifying the protocol each time.
Calculate and record the new starting condition
Record the counting method, dilution, viability assessment where relevant, target density, vessel growth area, number of vessels, suspension concentration and final volume. Keep units visible through the calculation.
Mix the suspension using a method that maintains uniformity without unnecessary mechanical stress, then distribute promptly and consistently.
Evaluate recovery at a predefined time
Check attachment, distribution and morphology at a consistent post-seeding time. A later endpoint alone may hide a poor initial attachment event followed by selective survival.
If recovery differs from the baseline, review the pre-passage state, dissociation exposure, cell suspension quality, seeding calculation, vessel preparation and incubation transition before changing multiple downstream conditions.