OECD Guideline 474

In Vivo Micronucleus Testing

The "OECD Guideline for the Testing of Chemicals, Mammalian Erythrocyte Micronucleus Test", was adopted on
September 26, 2014.

The required number of immature erythrocytes scored has increased from 2,000 to 4,000

OECD updated guideline 474 states, "At least 4,000 immature erythrocytes per animal should be scored for the incidence of micronucleated immature erythrocytes."

This is in contrast to the 2,000 cells previously required.

How we can help you:

Score 4,000+ cells in less than a minute using MicroFlow® kits. Complete a typical study in a single day.

Automated scoring methods are accepted and recommended (e.g., flow cytometry)

OECD updated guideline 474 states, "Counting sufficient immature erythrocytes in the peripheral blood or bone marrow of adult animals is greatly facilitated by using an automated scoring platform."

Also, "Comparative studies have shown that such methods, using appropriate calibration standards, can provide better inter- and intra-laboratory reproducibility and sensitivity than manual microscopic scoring."

How we can help you:

With Litron's MicroFlow kits, you will be using the most validated and peer-reviewed "automated scoring method" available. In fact, it was the MicroFlow method that was used for the comparative studies referred to in the guideline (Reference 1, Reference 2). This method is used by 16 of the top 20 pharma companies in the world, along with top CRO, medical device and chemical companies, among others.

Since 1999, MicroFlow kits have included "appropriate calibration standards" to ensure inter- and intra-laboratory reproducibility and sensitivity.

Rat peripheral blood is formally accepted

OECD updated guideline 474 states, "Mice, rats, or another appropriate mammalian species may be used. When peripheral blood is used, it must be established that splenic removal of micronucleated cells from the circulation does not compromise the detection of induced micronuclei in the species selected. This has been clearly demonstrated for mouse and rat peripheral blood."

This acceptance allows the micronucleus test to be easily integrated into general toxicology or other genetox studies.

How we can help you:

Use MicroFlow rat blood kits to discriminate between mature and immature erythrocytes using the anti-CD71 antibody.

With only a few drops of blood you can integrate rat MN analyses into your existing studies.

More flexibility in dosing and sampling times

OECD updated guideline 474 states, "...If three or more daily treatments are used ... peripheral blood should be collected no later than 40 hours after the last treatment" [emphasis added]

"This treatment option accommodates combination of the comet assay ...and integration of the micronucleus test with repeated-dose toxicity studies."

How we can help you:

MicroFlow kits are particularly well suited to take advantage of this flexibility. With only a few drops of blood you can easily integrate micronucleus analyses into your existing studies.

Concurrent positive controls are no longer required

OECD updated guideline 474 states, "When a concurrent positive control group is not included, scoring controls... should be included in each experiment."

How we can help you:

Create scoring controls that are both reproducible and robust over long periods of time. This is accomplished using the MicroFlow method's ultracold fixation and Long Term Storage Solution.

Next Steps


If you're interested in companies that perform complete micronucleus testing (not just analyses) using these flow cytometric methods

Contact Us

For more information about regulatory use of In Vivo MicroFlow kits

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To get a copy of the
OECD 474 Guideline

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