A: Whole-mount LacZ staining of Adamts18−/− E12.5 lungs showing tip expression of Adamts18. B: LacZ section of Adamts18−/− of an individual tip with a dashed line highlighting distribution of Adamts18 expression within the epithelium. C, D: Adamts18+/+ (C) and Adamts18−/− (D) cryosections of lungs immunostained with Sox9, EdU, and Hoechst 33342. Dashed lines represent the Sox9+ cell population identified as tip cells. E-H: Kidney Adamts18+/+ (E, G) and Adamts18−/− (F, H) cryosections immunostained with Ret, EdU, and Hoechst 33342. G and H are higher magnifications of white boxes in E and F, respectively. I: Percentage of EdU cells in the tip populations of lungs (portion of Sox9+ population represented by dashed line showcased in B-D) and kidneys (Ret+ population) in Adamts18+/+ and Adamts18−/− (n = 5). There is no significant difference in percent of EdU+ cells within the tip populations of lungs or kidneys. Error bars are SD and significance was determined by a two-tailed t-test. All organs collected and quantified had somite counts of 51 or 52. Line in A = 200μm; Line in B-H = 20μm.