Localization and relative abundance of elastin and density of secondary septal crests in control and embolised fetal lung tissue. Light micrographs depicting the localization of elastin (purple-black) staining in control (A), 1d PPE + 15d (B), and 5d PPE + 16d (C) lung tissue. Nuclei and cytoplasm are counterstained yellow. The arrows in A-C indicate secondary septal crests and the arrow-heads indicate deposition of elastin throughout the primary septal wall and around the base of alveoli in PPE fetuses (B-C). The scale bar in (C) represents 10 μm in images A-C and the scale bar in F represents 10 μm in images D-F. The relative abundance of elastin (G) was decreased in 1d PPE + 15d and 5d PPE + 16d fetuses relative to control fetuses (* p < 0.05). The density of secondary septal crests in the lung parenchyma (H) of 1d PPE + 15d fetuses was lower than in control fetuses (*p < 0.001) and lower in 5d PPE + 16d fetuses relative to 1d PPE + 15d fetuses and control fetuses (**p < 0.05).