Development of the bronchial tree in Monodelphis domestica (Marsupialia)

The Gray Short-tailed opossum (Monodelphis domestica) is a pouchless marsupial from Brazil. The newborn Monodelphis domestica represents the morphotype of the marsupial and mammalian neonate and is suitable to inform on the evolution of the mammalian lung. Phase-contrast X-ray computed tomography (Micro-CT) has been applied to three-dimensionally reconstruct the bronchial tree of Monodelphis domestica in order to reveal the timeline of branching morphogenesis during the postnatal period. Based on the reconstructions, the generation of end-branching airways, the median and maximum generation and the number of branches were calculated for each pulmonary lobe. The lung development was examined from embryonic day 13, during the postnatal period (neonate to 57 days) and in adults. The lung of the newborn Monodelphis domestica has a primitive appearance. Lobar bronchioles and first segmental bronchioles form a simple system of branching airways that end in a number of large terminal air spaces. During the postnatal period development, differentiation and expansion of the bronchial tree takes place. The fundamental bronchial tree, consisting of lobar, segmental and sub-segmental bronchioles, is present by day 14. By 35 days a mature bronchial tree, including respiratory bronchioles and alveolar ducts is established. A peculiarity found in the mature lung of Monodelphis domestica, alveoli located at the walls of large conducting airways, might be a remnant of the transformation of former respiratory epithelium into bronchiolar epithelium and results from the postnatal formation of the bronchial tree in a functioning lung. In marsupials, the process of branching morphogenesis follows similar patterns as described in placentals. However, while this developmental process takes place intrauterine in the placental fetus, it is shifted to the postnatal period in marsupial species. Lung maturation in general and the branching morphogenesis in particular seems to be highly conservative within mammalian evolution. This data set contains original files (videos, images, tables, data sheets) to the publication "3-D-Reconstruction of the bronchial tree of the Gray short-tailed opossum (Monodelphis domestica) in the postnatal period". Images taken from all perspectives and videos of the reconstructed bronchial tree allow for a thoroughly 3-dimensional impression and are a supplement to the published article.