title: Spleen pigmentation in young C57BL mice is caused by accumulation of melanin.
abstract: It has been previously reported that in 2 C57BL mouse sublines a dark pigmentation of the cranial part of the spleen occurs in up to 30% of the animals within the populations. It was not clear whether this discoloration is caused by melanosis, lipofuscinosis or haemosiderosis. With the use of light and electron microscopy of stained spleen sections, we identified the pigment in 14 out of 60 C57BL mice aged 8-10 wks. In the mice with pigmented spleens there was accumulation of melanin, predominantly in melanophores. Literature data indicate that apart from melanin, lipofuscin and haemosiderin can be observed in splenic macrophages provided that the mice are older than those studied by us. We conclude that melanin is the principal pigment causing spleen discoloration in young C57BL mice. Splenic melanosis displays inter-individual variation, but its relevance from a pathophysiological point of view remains obscure.
authors.affiliation: Department of Laboratory Animal Science, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: van der Heijden
authors.forename: J E
authors.initials: JE
authors.lastname: van Dijk
authors.forename: A G
authors.initials: AG
authors.lastname: Lemmens
authors.forename: A C
authors.initials: AC
authors.lastname: Beynen
mesh_terms: D000818:Animals; D001835:Body Weight; D006485:Hemosiderin / Q000032:analysis; D007501:Iron / Q000032:analysis; D007668:Kidney / Q000737:chemistry; D008062:Lipofuscin / Q000032:analysis; D008099:Liver / Q000737:chemistry; D008297:Male; D008543:Melanins / Q000032:analysis*; D008544:Melanocytes / Q000737:chemistry / Q000648:ultrastructure; D008548:Melanosis / Q000209:etiology / Q000662:veterinary*; D051379:Mice; D008810:Mice, Inbred C57BL; D009929:Organ Size; D010858:Pigmentation; D012376:Rodent Diseases / Q000209:etiology*; D013154:Spleen / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D008062:Lipofuscin; D008543:Melanins; D006485:Hemosiderin; D007501:Iron