The hyaline membranes are composed of fibrin-rich edema fluid mixed with the cytoplasmic remnants of necrotic epithelial cells. The type II epithelial cells undergo proliferation in an attempt to regenerate to alveolar lining. As the process continues, the hyaline membranes diminish and the type II cells increase, while there is interstitial thickening and increasing numbers of mononuclear inflammatory cells. The next stage, the proliferative or organizing stage of DAD, occurs after 1 to 2 weeks. The exudates organize, and interstitial thickening becomes more prominent.
Fibroblasts begin laying down more collagen.