Figure 2

Distribution of α SMA-immunoreactivity in pulmonary arteries. (A) Course of a pulmonary artery from the bronchus (left) to the pleural surface (right). (B) A supernumerary branch (arrow) leaves a pulmonary artery that lies close to a bronchus (Br). (C) Magnification of the boxed area in A. The artery displays a dense mesh of α SMA-immunoreactive cells that becomes wider in distal direction and finally vanishes. To the left, a branch with almost no α SMA-immunoreactive cells leaves the artery. (D) Higher magnification from C that clearly depicts the branched morphology of α SMA-immunoreactive cells. (E) Transition of circular into mesh-like organization of α SMA-immunoreactive cells in the arterial wall. (F) At a branch point, the organization pattern of α SMA-immunoreactive cells changes. Only few if any α SMA-immunoreactive cells are visible in the branches (arrows). (G) Intra-acinar artery devoid of α SMA-immunoreactive cells. (G') Differential interference contrast image of G. Bars in A, B = 100 μm; in C-G' = 50 μm.