title: The non-proliferative nature of ascidian folliculogenesis as a model of highly ordered cellular topology distinct from proliferative epithelia.
abstract: Previous studies have addressed why and how mono-stratified epithelia adopt a polygonal topology. One major additional, and yet unanswered question is how the frequency of different cell shapes is achieved and whether the same distribution applies between non-proliferative and proliferative epithelia. We compared different proliferative and non-proliferative epithelia from a range of organisms as well as Drosophila melanogaster mutants, deficient for apoptosis or hyperproliferative. We show that the distribution of cell shapes in non-proliferative epithelia (follicular cells of five species of tunicates) is distinctly, and more stringently organized than proliferative ones (cultured epithelial cells and Drosophila melanogaster imaginal discs). The discrepancy is not supported by geometrical constraints (spherical versus flat monolayers), number of cells, or apoptosis events. We have developed a theoretical model of epithelial morphogenesis, based on the physics of divided media, that takes into account biological parameters such as cell-cell contact adhesions and tensions, cell and tissue growth, and which reproduces the effects of proliferation by increasing the topological heterogeneity observed experimentally. We therefore present a model for the morphogenesis of epithelia where, in a proliferative context, an extended distribution of cell shapes (range of 4 to 10 neighbors per cell) contrasts with the narrower range of 5-7 neighbors per cell that characterizes non proliferative epithelia.
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Institut des Sciences de l'Evolution (ISE-M), CNRS, Montpellier, France.
authors.forename: Karim
authors.initials: K
authors.lastname: Azzag
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Laboratoire de Mécanique et Génie Civil (LMGC), CNRS, Montpellier, France.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Chelin
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Institut des Sciences de l'Evolution (ISE-M), CNRS, Montpellier, France.
authors.forename: François
authors.initials: F
authors.lastname: Rousset
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Institut des Sciences de l'Evolution (ISE-M), CNRS, Montpellier, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Le Goff
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Institut des Sciences de l'Evolution (ISE-M), CNRS, Montpellier, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Martinand-Mari
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Institut de Génétique Humaine (IGH), CNRS, Montpellier, France.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Martinez
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Laboratoire de Mécanique et Génie Civil (LMGC), CNRS, Montpellier, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Maurin
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; INSERM U1040, Montpellier, France; CHU Montpellier, Institut de Biothérapie, Montpellier, France.
authors.forename: Martine
authors.initials: M
authors.lastname: Daujat-Chavanieu
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Institut des Sciences de l'Evolution (ISE-M), CNRS, Montpellier, France.
authors.forename: Nelly
authors.initials: N
authors.lastname: Godefroy
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Laboratoire de Mécanique et Génie Civil (LMGC), CNRS, Montpellier, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Averseng
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Centre de Recherche de Biochimie Macromoléculaire (CRBM), CNRS, Montpellier, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Mangeat
authors.affiliation: Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France; Institut des Sciences de l'Evolution (ISE-M), CNRS, Montpellier, France.
authors.forename: Stephen
authors.initials: S
authors.lastname: Baghdiguian
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology*; D048430:Cell Shape / Q000502:physiology; D004331:Drosophila melanogaster / Q000166:cytology; D004847:Epithelial Cells / Q000166:cytology*; D004848:Epithelium / Q000254:growth & development*; D009024:Morphogenesis / Q000502:physiology*; D014561:Urochordata / Q000166:cytology