Trichome staining and modified Ashcroft scores of controls and irradiated lungs at 24 weeks and later after irradiation. Panel A: Trichome staining of representative lung tissue sections reveal areas of increased collagen deposition and in lungs irradiated at 24 weeks after 12.5 Gy irradiation, which are notably absent in 10 Gy irradiated lungs at 24 and 36 weeks. Panel B: Modified Ashcroft scores of controls and irradiated lungs at 24 weeks and later.