A-D: Whole-mount immunostaining with proximal (Sox2) and distal (Sox9) progenitor markers appear similar between wildtype and Adamts18−/− E12.5 lungs. E-J: Section immunostaining on E16.5 lungs with differentiated cell types, highlighting a lack of mucosal cells (Muc5ac), alveolar epithelial type 2 cells (Sftpc), and ciliated cells (Tuba4a) in Adamts18−/− compared to wildtype. I: qPCR analysis on Adamts18−/− and wildtype lungs at E16.5, E17.5, and adult stages. Black bars are the average between the biological triplicates and significance was determined by a two-tailed t-test. * = p ≤ 0.05, ** = p ≤ 0.01, *** = p ≤ 0.001. Line in A-D = 200μm, line in E-J = 20μm.