Figure 6.

Persistence of new lymphatic vessels after treatment. (A and B) Weight of lungs and bronchial lymph nodes (A) and abundance of tracheal lymphatic vessels and blood vessels (B) in pathogen-free mice (0), mice infected with M. pulmonis for 2 or 4 weeks (2 and 4), and mice infected for 2 weeks and then treated with oxytetracycline for 2 to 12 weeks (2 + 2 through 2 + 12). The weight of both organs increased after infection and decreased toward normal after treatment. Airway blood vessels (green) showed a similar pattern, whereas lymphatic vessels (red) proliferated after infection but regressed little, even after 12 weeks of treatment. *P < 0.05 vs. pathogen-free group; P < 0.05 vs. 2-week-infected group without treatment. (C and D) Confocal micrographs showing tracheal lymphatic vessels (red) and blood vessels (green) after infection for 2 weeks and then oxytetracycline treatment for 8 weeks. Blood vessels regressed almost to the pathogen-free state. Lymphatic vessels showed some changes but regressed only slightly; lymphatic vessels with constrictions and no LYVE-1 immunoreactivity in some cells are indicated by arrows. (D) Enlargement of the boxed area in C. Scale bar in D applies to both figures: 100 μm in C, 25 μm in D.