title: The equine thymus microenvironment: a morphological and immunohistochemical analysis.
abstract: We characterized herein the microarchitecture of the equine thymus along with post-natal development (6 months-->18 years). Thymuses showed an involutional process, beginning before the puberty and defined by five histological grades, which consider the progressive cortical thymocyte depletion, shrinkage and rearrangement of the epithelial network and increase in extracellular matrix (ECM). A second feature of the equine thymus was the presence of eosinopoiesis, erythropoiesis, mastocytopoiesis and plasmacytogenesis. Additionally, lymphatic vessels, full of lymphocytes, were particularly prominent. Distribution of ECM proteins was heterogeneous, being denser in the medulla, as well as basement membranes of capsule, septa and perivascular spaces, thus similar to the patterns seen in other mammals. In vitro, horse thymic nurse cells produce ECM proteins, which are relevant in thymocyte/epithelial cell interactions. In conclusion, the equine thymus presents morphological and involutional characteristics similar to other mammals, exhibiting particular features, as prominent non-lymphoid hematopoiesis and lymphatic vessels.
authors.affiliation: Laboratory on Thymus Research, Department of Immunology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Av. Brasil 4365, Manguinhos, 21045-900 Rio de Janeiro, Brazil.
authors.forename: Ellen C
authors.initials: EC
authors.lastname: Contreiras
authors.forename: Henrique L
authors.initials: HL
authors.lastname: Lenzi
authors.forename: Maria N L
authors.initials: MN
authors.lastname: Meirelles
authors.forename: Luzia F G
authors.initials: LF
authors.lastname: Caputo
authors.forename: Theresinha J C
authors.initials: TJ
authors.lastname: Calado
authors.forename: Déa M S
authors.initials: DM
authors.lastname: Villa-Verde
authors.forename: Wilson
authors.initials: W
authors.lastname: Savino
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D024141:Collagen Type IV / Q000032:analysis; D004804:Eosinophils / Q000166:cytology; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology; D004848:Epithelium / Q000033:anatomy & histology / Q000502:physiology; D005109:Extracellular Matrix / Q000737:chemistry / Q000502:physiology; D005260:Female; D005353:Fibronectins / Q000032:analysis / Q000502:physiology; D006736:Horses; D007150:Immunohistochemistry; D007797:Laminin / Q000032:analysis / Q000502:physiology; D042601:Lymphatic Vessels / Q000033:anatomy & histology / Q000166:cytology; D008214:Lymphocytes / Q000166:cytology; D008297:Male; D008407:Mast Cells / Q000166:cytology; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D013950:Thymus Gland / Q000033:anatomy & histology* / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D000906:Antibodies; D024141:Collagen Type IV; D005353:Fibronectins; D007797:Laminin