Table 2 Quantitative morphological data obtained by light microscopy: absolute volumes (mm3).
| Absolute volumes (mm3) | Room air | 10 ppm NO2 | NO2/room air | ||||
|---|---|---|---|---|---|---|---|
| 3 days | 21 days | 49 days | 3 days | 7 days | 21 days | 21 and 28 days | |
| Fixed lung | 4920 (549) | 5496 (435) | 7140 (213)* | 4768 (592) | 6322 (661)† | 7623 (514)‡ | 7665 (1107)‡ |
| Non‐parenchyma | 689 (76) | 703 (104) | 725 (86) | 626 (108) | 758 (177) | 733 (62) | 752 (129) |
| Parenchyma | 4231 (547) | 4793 (352) | 6415 (190)* | 4142 (564) | 5564 (553)† | 6891 (501)‡ | 6913 (1002)‡ |
| Airspace | 3768 (525) | 4316 (332) | 5765 (204)¶ | 3546 (556) | 4941 (486)¶ | 6161 (487)¶ | 6275 (962)¶ |
| Alveolar macrophages | 47 (22) | 47 (20) | 39 (12) | 155 (59)** | 75 (29) | 103 (43)§ | 34 (6) |
| Granulocytes (PMNs) | 5.6 (2.8) | 7.1 (3.2) | 7.4 (3.3) | 13.6 (7.8) | 9.9 (5.5) | 16 (8.9) | 7.8 (0.3) |
| Other cells | 8.2 (3.6) | 14 (6.8) | 15.4 (5.1) | 19.2 (4.4) | 16.8 (7.4) | 27.3 (11)** | 13 (2.3) |
| Alveolar septal wall | 463 (62) | 477 (40) | 650 (52)¶ | 596 (86) | 624 (112)¶ | 729 (93)¶ | 638 (74)¶ |
| Mean thickness (µm) | 4.2 (0.5) | 4 (0.2) | 4.1 (0.4) | 5.3 (0.6)** | 5 (0.5)** | 4.7 (0.4) | 4.2 (0.3) |
| Mean chord length (µm) | 56.1 (5.7) | 65.5 (4.4) | 73.3 (10.2)†† | 56.2 (6.7) | 76.6 (7.6)†† | 78.9 (8)* | 72.8 (9)†† |
| Volume‐weighted mean airspace volume (106 µm3) | 4.83 (1.35) | 5.36 (1.92) | 6.36 (1.92)¶ | 3.17 (0.45) | 6.88 (2.11)¶ | 7.49 (0.88)¶ | 7.15 (0.73)¶ |
| Surface density (1/mm) | 52.4 (3.7) | 49.7 (5.3) | 48.7 (2.7) | 54.9 (6.1)§§ | 44.4 (3.3)‡‡ | 44.8 (4.1)‡‡ | 45.3 (2.3)‡‡ |
| Total alveolar surface area (cm2) | 2205 (214) | 2377 (240) | 3125 (161)‡ | 2253 (180) | 2479 (384) | 3078 (269)‡ | 3121 (433)‡ |
Significant differences among groups at p<0.05 (one‐way analysis of variance followed by post hoc pairwise multiple comparisons, Tukey's test) are indicated as follows:
*vs room air 3 days, 21 days; NO2 3 days.
†vs room air 3 days, 21 days; NO2 3 days, 21 days; NO2/room air.
‡vs room air 3 days, 21 days; NO2 3 days, 7 days.
§vs NO2/room air.
¶vs room air 3 days, 21 days.
**vs room air 3 days, 21 days, 49 days; NO2/room air.
††vs room air 3 days; NO2 3 days.
‡‡vs NO2 3 days.
§§vs NO2 7 days, 21 days; NO2/room air.