Figure 4.

gpt MFs in the lungs of mice singly and multiply intratracheally instilled with particles. Male mice were treated with single (0.2 mg per animal) or multiple (0.2 mg per animal × 4) doses of particles, and mice were sacrificed 12 (single) and 8 (multiple) weeks after particle administrations. Mean values ± SD are shown. An asterisk (*, **) denotes p < 0.05 (*) and p < 0.01 (**) in a Student's t-test of MF of particle-treated vs. the corresponding vehicle-control mice.