title: Extracellular Assembly of the Elastin Cable Line Element in the Developing Lung.
abstract: In the normal lung, a dominant structural element is an elastic "line element" that originates in the central bronchi and inserts into the distal airspaces. Despite its structural importance, the process that leads to development of the cable line element is unknown. To investigate the morphologic events contributing to its development, we used optical clearing methods to examine the postnatal rat lung. An unexpected finding was numerous spheres, with a median diameter of 1-2 µm, within the primary septa of the rat lung. The spheres demonstrated green autofluorescence, selective fluorescent eosin staining, reactivity with carboxyfluorescein succinimidyl ester, and specific labeling with anti-tropoelastin monoclonal antibody-findings consistent with tropoelastin. The sphere number peaked on rat postnatal day 4 (P4) and were rare by P14. The disappearance of the spheres was coincident with the development of the cable line element in the rat lung. Transmission electron microscopy demonstrated no consistent association between parenchymal cells and sphere alignment. In contrast, the alignment of tropoelastin spheres appeared to be the direct result of interactions of scaffold proteins including collagen fibers and fibrillin microfibrils. We conclude that the spatial organization of the cable line element appears to be independent of tropoelastin deposition, but dependent on crosslinking to scaffold proteins within the primary septa. Anat Rec, 300:1670-1679, 2017. © 2017 Wiley Periodicals, Inc.
authors.affiliation: Laboratory of Adaptive and Regenerative Biology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Cristian D
authors.initials: CD
authors.lastname: Valenzuela
authors.affiliation: Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.
authors.forename: Willi L
authors.initials: WL
authors.lastname: Wagner
authors.affiliation: Laboratory of Adaptive and Regenerative Biology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Bennett
authors.affiliation: Laboratory of Adaptive and Regenerative Biology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Alexandra B
authors.initials: AB
authors.lastname: Ysasi
authors.affiliation: Laboratory of Adaptive and Regenerative Biology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Janeil M
authors.initials: JM
authors.lastname: Belle
authors.affiliation: Institute of Pathology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Molter
authors.affiliation: Institute of Pathology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.
authors.forename: Beate K
authors.initials: BK
authors.lastname: Straub
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH.
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH.
authors.forename: Zi
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Ackermann
authors.affiliation: Molecular and Integrative Physiological Sciences, Harvard School of Public Health, Boston, MA.
authors.forename: Akira
authors.initials: A
authors.lastname: Tsuda
authors.affiliation: Laboratory of Adaptive and Regenerative Biology, Brigham & Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Mentzer
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D005260:Female; D008168:Lung / Q000196:embryology* / Q000378:metabolism / Q000648:ultrastructure; D011247:Pregnancy; D017208:Rats, Wistar; D014333:Tropoelastin / Q000378:metabolism*
chemical_list: D014333:Tropoelastin
keywords: alveolarization; line element; lung development; murine; tropoelastin