图示：肺泡内巨噬细胞含铁血黄素沉着（呈褐色粗糙颗粒）。是红细胞血红蛋白降解后所产生和释放的。巨噬细胞能吞噬清除这种碎片，并使之得以循环利用。
The brown coarsely granular material in macrophages in this alveolus is hemosiderin that has accumulated as a result of the breakdown of RBC's and release of the iron in heme. The macrophages clear up this debris, which is eventually recycled.