title: Morphological and functional development of the interbranchial lymphoid tissue (ILT) in Atlantic salmon (Salmo salar L).
abstract: The interbranchial lymphoid tissue (ILT) of Atlantic salmon originates from an embryological location that in higher vertebrates gives rise to both primary and secondary lymphoid tissues. Still much is unknown about the morphological and functional development of the ILT. In the present work a standardized method of organ volume determination was established to study its development in relation to its containing gill and the thymus. Based on morphological findings and gene transcription data, the ILT shows no signs of primary lymphoid function. In contrast to the thymus, an ILT-complex first became discernible after the yolk-sac period. After its appearance, the ILT-complex constitutes 3-7% of the total volume of the gill (excluding the gill arch) with the newly described distal ILT constituting a major part, and in adult fish it is approximately 13 times larger than the thymus. Confined regions of T-cell proliferation are present within the ILT. Communication with systemic circulation through the distal ILT is also highly plausible thus offering both internal and external recruitment of immune cells in the growing ILT.
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway. Electronic address: alf.seljenes.dalum@nmbu.no.
authors.forename: Alf Seljenes
authors.initials: AS
authors.lastname: Dalum
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: David James
authors.initials: DJ
authors.lastname: Griffiths
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Elin Christine
authors.initials: EC
authors.lastname: Valen
authors.affiliation: LetSea Helgeland Havbruksstasjon AS, Sandnessjøen, Norway.
authors.forename: Karoline Skaar
authors.initials: KS
authors.lastname: Amthor
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Lars
authors.initials: L
authors.lastname: Austbø
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Erling Olaf
authors.initials: EO
authors.lastname: Koppang
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Charles McLean
authors.initials: CM
authors.lastname: Press
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Agnar
authors.initials: A
authors.lastname: Kvellestad
mesh_terms: D000818:Animals; D005260:Female; D005880:Gills / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D008221:Lymphoid Tissue / Q000166:cytology* / Q000254:growth & development*; D008297:Male; D020317:Salmo salar / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000254:growth & development
keywords: Diffuse MALT; Gill-associated lymphoid tissue; Leucocyte trafficking; Ontogeny; Proliferative T-cells; Stereology; Thymus