title: Intravital imaging of thymopoiesis reveals dynamic lympho-epithelial interactions.
abstract: T cell development occurs in the thymus. The thymic microenvironment attracts hematopoietic progenitors, specifies them toward the T cell lineage, and orchestrates their differentiation and egress into the periphery. The anatomical location of the thymus and the intrauterine development of mouse embryos have so far precluded a direct visualization of the initial steps of thymopoiesis. Here, we describe transgenic zebrafish lines enabling the in vivo observation of thymopoiesis. The cell-autonomous proliferation of thymic epithelial cells, their morphological transformation into a reticular meshwork upon contact with hematopoietic cells, and the multiple migration routes of thymus-settling cells could be directly visualized. The unexpectedly dynamic thymus homing process is chemokine driven and independent of blood circulation. Thymocyte development appears to be completed in less than 4 days. Our work establishes a versatile model for the in vivo observation and manipulation of thymopoiesis.
authors.affiliation: Department of Developmental Immunology, Max-Planck Institute of Immunobiology and Epigenetics, Stuebeweg 51, 79108 Freiburg, Germany.
authors.forename: Isabell
authors.initials: I
authors.lastname: Hess
authors.forename: Thomas
authors.initials: T
authors.lastname: Boehm
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001775:Blood Circulation; D002454:Cell Differentiation; D002465:Cell Movement; D060833:Cellular Microenvironment; D002634:Chemotaxis, Leukocyte; D053595:Embryonic Stem Cells / Q000166:cytology / Q000276:immunology; D004848:Epithelium / Q000196:embryology; D038041:Lymphopoiesis / Q000502:physiology*; D051379:Mice; D018448:Models, Immunological; D013601:T-Lymphocytes / Q000166:cytology* / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology* / Q000276:immunology; D015027:Zebrafish / Q000196:embryology / Q000235:genetics / Q000502:physiology