A-C: Whole-mount immunostaining of stage-matched Adamts18 E12.5 lungs with cytokeratin were scanned with OPT (n = 5; somite range = 49–51). D-F: Three-dimensional skeletal and segmentation models of lungs from A-C generated in Tree Surveyor. G-I: Dendrograms displaying the branching pattern for the lungs from A-C. Each lobe is color-coded: cranial = green, medial = pink, caudal = yellow, accessory = purple, left = blue. J-L: Dendrograms of each lung’s accessory lobe. M: Tree Surveyor global analysis quantification. Error bars are SD and significance was determined by a two-tailed t-test. ** = p ≤ 0.01, *** = p ≤ 0.001. Line = 200μm.