VEGFB protein expression within the rat lung. Images (A-D) are taken from a control lung, while images (E-J) are from a hypoxic lung. Panels A and E show low magnification images of control and hypoxic tissue. VEGFB protein was expressed within alveolar wall and type II pneumocytes (black arrows, B and F) and the wall of intra-acinar blood vessels (C and G). Panels (I) and (J) show stained and unstained macrophages from the same hypoxic lung (black arrows). A similar pattern of macrophage staining was observed in control lungs (not shown). Images (D) and (H) show control (D) and hypoxic (H) lung tissue to which Isotype matched IgG (mouse IgG1, R&D, UK) was added to the slide instead of primary antibody. No staining was observed in the IgG slides, therefore indicating that the staining observed is indeed specific for VEGFB protein. All images were taken with an x100 objective, the scale bar represents 20 μm. (K) The volume fraction of VEGFB protein was significantly decreased following 14 days exposure to chronic hypoxia compared to its matched normoxic control. The black bar represents the mean value in each group. * signifies significant difference from matched control (p < 0.05, T-Test, post-hoc Mann Whitney U). N = 7 per group.