Dorsal skin of mice was exposed topically to either 200 µL of acetone or NM (3.2 mg) in 200 µL acetone. After 12, 24, 72 and 120 h of NM exposure, mice were sacrificed and dorsal skin tissue sections (5 µm) were processed, H&E stained and analyzed as detailed under Materials and Methods. Panels A and C are representative H&E stained skin sections (400× magnification) showing epidermal thickness from vehicle control and 24 h exposed NM exposed skin tissue in SKH-1 and C57BL/6 mice, respectively. Panel E (i–iii) and G (i–iii) are representative H&E stained skin sections (100× magnification), and E (iv–vi) and G (iv–vi) are representative H&E stained skin sections (400× magnification) showing microvesication from vehicle control and 12–120 h NM exposed skin tissue in mice. These NM-related histopathological changes were assessed as detailed under materials and methods, and calculated as percent length of mice skin epidermis showing epidermal thickness (B and D) and microvesication (F and H). Data presented are mean ± SEM of 3–5 animals in each group. *, p<0.05 compared to respective vehicle control; VC, vehicle control; NM, nitrogen mustard; e, epidermis; d, dermis; red arrows, microvesication (epidermal and dermal separation); pink arrows, microvesication within the epidermal layer.