Fig. 4.

GFP⁺ cells present in areas of focal pulmonary fibrosis. Representative histologic samples with Trichrome Masson staining for collagen (blue, A–D) in paraffin-sectioned lungs and confocal microscopy images (E, F) of lung cryosections 2 months after instillation of bacteria into the lungs. A Lungs of control mice instilled with PBS. No signs of fibrosis and collagen deposition. B–D Lungs from mice instilled with bacteria, deposition of collagen and dense cell infiltration are present in peribronchial and perivascular interstitium, magnification ×25. E–G Confocal microscopy images of the same lungs as presented in B–D. GFP⁺ cells are bright green. Foci of fibrosis with multiple GFP⁺ cells in perivascular and peribronchial interstituim in E and F (costaining PI, red, magnification ×25). G GFP⁺ cells form clones of vimentin-positive cells. Tissues were stained for vimentin with Texas Red secondary antibody (red). Split image: upper-left: red fluorescence (vimentin) only; upper-right: green fluorescence (GFP) only; lower-left: combined image, magnification ×65