||This article does not cite any sources. (December 2009)
The hematon was first defined in 1988 as the primary fundamental unit of haematopoiesis, the formation of blood cells.
The hematon is believed to be a low density multicellular spheroid approximately 100-500 micrometres in diameter. These cells are arranged into a complex 3-D network and surround a system of highly vascularised and arbourised fibrous cords which run throughout the structure. The spheroid is composed of a central core of adipocytes/preadipocytes cells, mesenchymal cells, recticular cells and macrophages. This core is surrounded by a peripheral layer of myeloid, erythroid and megakaryocyte progenitor cells and their progeny.