Fig. 5.

Topical application of NM causes an increase in the number of mast cells and macrophages in the skin of male SKH-1 hairless and C57BL/6 mice. Mice were exposed topically to either 200 µL of acetone alone or with NM (3.2 mg) in 200 µL acetone for 12–120 h and skin tissue was collected, processed, sectioned and subjected to toluidine blue staining (A–D) or F4/80 IHC (E–H) as detailed under materials and methods. NM-induced increase in mast cell numbers in toluidine blue stained skin sections from SKH-1 hairless and C57BL/6 mice is shown in representative pictures (A and C), which was further quantified (B and D) as detailed under materials and methods. NM-induced increase in macrophages in F4/80 IHC stained skin sections from SKH-1 hairless and C57BL/6 mice is shown in representative pictures (E and G), which was further quantified (F and H) as detailed under materials and methods. Positive stained cells (mast cells and macrophages) were counted per mm² field in randomly selected five fields per sample (×400 magnification) as detailed in materials and methods. Data presented are mean ± SEM of three-five animals of each group. Statistical significance of difference between the NM exposed and control groups were determined by one way ANOVA followed by Bonferroni t-test for pair wise multiple comparisons. *, p<0.001 compared to control group. e, epidermis; d, dermis; red arrows, mast cells and macrophages.