Figure 8

Percentage of fibrous tissue stained with aniline blue. The percentage of fibrous tissue with 2 week exposure to 40% oxygen was significantly increased as compared to that with 2 week exposure to 21% oxygen. There was no significant difference among the 90% oxygen exposure groups. Fibrous tissue levels in 2 and 16 week 21% oxygen exposure control lungs were not lower as compared to that in pre-exposure. Values are expressed as means ± SD. n = 10 in the pre-exposure group; n = 8 (2 weeks), 10 (4 weeks), 6 (8 weeks) and 6 (16 weeks) in the 40% oxygen exposure groups; n = 4 (2 weeks), 7 (4 weeks), 6 (8 weeks) and 5 (16 weeks) in the 21% oxygen exposure groups; n = 5 (72 hours) and 9 (96 hours) in the 90% oxygen exposure groups. * p < 0.01 as compared to the value of the 21% exposure duration-matched control.