FIG. 4.

Delayed lung development in fibulin-1-deficient mice at stage E18.5 and 1 day after birth. (A and B) HE staining of fibulin-1-deficient animals shows improperly expanded sacculi in the lungs of spontaneous breathing E18.5 embryos and enlarged sacculi with thickened septa at perinatal day 1 compared to heterozygous controls. (B and C) Immunostaining for the endothelial marker PECAM-1 (B) and epithelial marker cytokeratin (C) demonstrates the proper arrangement of both cell types. Examples of sacculi that are not expanded in homozygous animals are indicated by white asterisks. Bar, 100 μm.