Figure 3.

TIMP-3–null mice demonstrate alveolar air space enlargement. (a) Hematoxylin and eosin–stained lung sections (scale bar, 100 μm). (b) Quantification of mean linear intercept. A progressive increase in mean linear intercept was seen in the lungs of knockout animals, indicative of an increase in alveolar size with increasing age of the animal (2 weeks: control, n = 10; null, n = 5; 4 months: control, n = 10; null, n = 6; 8 months: control, n = 13; null, n = 10; aged: control, n = 17; null, n = 20; ± SD). At all ages examined, air space size was significantly increased in the knockout animals compared with controls (two-tailed Student’s t test; 2 weeks, P < 0.04; 4 months, P < 0.03; 8 months, P < 2 × 10^–10; aged animals, P < 5 × 10^–10).