Table 1. NM exposure caused infiltration of inflammatory cells (PMNs) in the dermis of SKH-1 hairless and C57BL/6 mice following 12–120 h of its exposure.

SKH-1
Exposure	VC	12 h NM	24 h NM	72 h NM	120 h NM
Inflammatory cells	+	+++	+++	+++	++
C57 BL/6
Exposure	VC	12 h NM	24 h NM	72 h NM	120 h NM
Inflammatory cells	+	++	+++	++	++

+, Few (less than 100); ++, moderate (100–1000); +++, high (more than 1000) inflammatory cells per skin section (at 400×); VC, vehicle control.