Histochemical staining of lipid accumulation by Oil Red O in differentiating primary rat preadipocytes cultured in medium with (OTA+) or without ochratoxin A (OTA-) and quercetin (QCT) at various concentrations. Cells were scanned both naive (A) and after histochemical staining with Oil Red O (B), magnification 100 ×. The absorbance of the Oil Red O eluate was measured at 500 nm (C). The results, presented as mean ± mean error (SEM), were analyzed by two-way ANOVA with factors QCT and OTA, followed by Bonferroni post-hoc test. The level of statistical significance considered for factor OTA was *** p < 0.001, and for factor QCT ## p < 0.01; ### p < 0.001.