Normochromatic erythrocytes

There was no increase in the incidence of micronucleated normochromatic erythrocytes or polychromatic erythrocytes in the peripheral blood of male and female mice exposed to 1,000, 4,000, or 10,000 ppm... 

Ciranni et al. (1988) found no evidence of fetal cellular toxicity, as measured by a reduction in the polychromatic erythrocyte/normochromatic erythrocyte... 

The micronucleus assay may be used not only for the detection of acute but also chronic genetic damage. In mice, chromosomal breakage in bone marrow erythroblasts produces an accumulation of micronuclei in normochromatic erythrocytes in peripheral blood and there is little, if any, selective removal of micronucleated cells from circulation. This is not the case with rats, which limits their usefulness in long-term studies using peripheral blood. 

Decalin was not mutagenic in bacterial assays in vitro but caused a small but significant increase in micronucleated normochromatic erythrocytes in male mice treated in vivo "... 

No significant increases in the frequency of micronucleated normochromatic erythrocytes were found in mice exposed to indium phosphide for 14 weeks. ... 

PCE—polychromatic erythrocytes NCE—normochromatic erythrocytes MPC—micronucleated polychromatic erythrocytes 90 CD-I mice (or rats)... 

The evaluation of micronuclei frequencies in peripheral blood polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) permits an assessment of both recently induced and chronically accumulated bone marrow damage. PCEs have a life span of about 24 hours and are good indicators of acute damage. NCEs have a life span of about 30 days and are good indicators of chronic damage. A... 

Positive result - = negative result (+) = weakly positive result DNA = deoxyribonucleic acid NCEs = normochromatic erythrocytes PCEs = polychromatic erythrocytes RNA = ribonucleic acid... 

Rithidech K, Au WW, Ramanujam VMS, et al. 1988. Persistence of micronuclei in peripheral blood normochromatic erythrocytes of subchronically benzene-treated male mice. Environ Mol Mutagen 12 319-329. 

In the micronucleus test, mice are given the test substance by intraperitoneal injection. Mice ai e killed 24 or 48 h after treatment and the femoral marrow cells are smeared on glass slides, fixed, stained and the numbers of micronucleated polychromatic erythrocytes and of micronucleated normochromatic erythrocytes are recorded. The numbers of micronucleated erjdhrocytes and the proportion of polychromatic erythrocytes relative to the total erythrocytes are evaluated by observing 1000 erythrocytes on the same slide. 

Reticulocytes, or polychromatic erythrocytes, are newly formed, immature red blood cells. These are larger than red blood cells and have retained some ribosomal RNA. These cells are detectable from normochromatic erythrocytes, mature erythrocytes that lack ribosomes, by their staining properties. Micronuclei are small nuclei, separate from and additional to the main nuclei of the cell. Micronuclei are... 

Rodents are typically administered a single dose of the test material. To obtain micronucleus information from a subgroup of a larger, repeated daily dose toxicity study lasting over 4 weeks, the ratio of micronucleated mature (normochromatic) erythrocytes in the peripheral blood to mature erythrocytes are determined. As long as there is no proof that the test material or a metabolite cannot act on the bone marrow, this assay may be used. 

Typically, micronucleus induction is measured in bone marrow PCEs after acute treatment. After repeated administration, it is also advisable to evaluate the induction of micronuclei in mature or normochromatic erythrocytes (NCEs). As erythrocytes persist for about one month in peripheral blood (named reticulocytes), the measurement of micronucleated reticulocytes in peripheral blood is considered equally acceptable in any species, provided that the spleen does not remove the micronucleated erythrocytes from blood and that both aneugens and clastogens are efficiently detected (see more in assays limitations and confounding factors section). Micronuclei are generally analyzed in the youngest (i.e., immature) reticulocytes in peripheral blood. 

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