Histological images from lungs of papain- and saline-treated hamsters. (A) control + saline (CS): animals treated with approximately 0.3 mL of saline only; (B) emphysema 20 mg/mL (E20): animals treated with approximately 0.3 mL of 20 mg/mL papain in saline; and (C) emphysema 40 mg/mL (E40): animals treated with approximately 0.3 mL of 40 mg/mL papain in saline. Animals were euthanized after 60 days. Hematoxylin and eosin (H & E) images are shown at 50× magnification. Alveolar destruction was determined by the number of times that a predetermined group of coherent lines (1.25 mm2 of total area and 1.50 mm of total length) crossed the parenchymal structures. The lesser these structures are crossed, the more extensive is the lesion.
Tonon et al. BMC Musculoskeletal Disorders 2013 14:39 doi:10.1186/1471-2474-14-39