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Bone marrow - nonneoplastic



Reviewers: Dragos Luca, M.D. (see Reviewers page)
Revised: 18 October 2012, last major update September 2012
Copyright: (c) 2001-2012, PathologyOutlines.com, Inc.


● Bone forming cell that arises from marrow mesenchymal (stromal) cells, unlike osteoclasts which are of hematopoietic origin
● Along endosteal surface of bony trabeculae or along margins in marrow smears
● Common in children; in adults associated with various diseases and healing biopsy sites
● Synthesize angiopoietin and osteopontin, which inhibit hematopoietic stem cell proliferation (Br J Haematol 2006;134:467, J Clin Invest 2006;116:1195)
● Synthesize and transport collagenous matrix, initiate and regulate mineralization, control removal of bone via osteoclasts
● When active, are plump and present on bone surface; eventually are encased within the collagen they produce and get flattened (and become osteocytes)
● Activity is promoted by physical activity (Wolf’s law of bone adaptation)
● Express parathormone receptors (mediates the activation of osteoclasts) and vitamin D receptor
● Control osteoclast activity via parathyroid hormone (parathormone), PHRP (Parathyroid hormone related protein), IL-1 and TNF alpha
● Digestion of bone by osteoclasts releases cytokines and growth factors for osteoblasts


Interaction of osteoblasts and hematopoietic stem cells

Key functions and regulation of osteoblasts

Micro description

● Large (25-50 microns), often oval, with abundant blue-gray cytoplasm and perinuclear hof separated from the nucleus (unlike plasma cells)
● Nucleus is markedly eccentric and round / ovoid with one or more nucleoli

Micro images



Osteoblasts in marrow smear are twice as big as plasma cells, have abundant blue cytoplasm, eccentric nucleus and often single nucleolus

Positive stains

● Alkaline phosphatase, estrogen receptor, parathyroid hormone and RANKL
● Also CD10, CD44, CD53, CD56, IL-12, IL-18 and IFN-gamma (Biosci Rep 2006;26:39)
● Cells in culture express CD11b, CD13, CD16, CD20, CD23, CD25, CD34, CD44, CD54, CD80, CD86 and HLA-DR (Cell Physiol Biochem 2002;12:359)

Negative stains

● Cells in culture are negative for CD3, CD14, CD15, CD45 and CD68

Electron microscopy description

● Resemble fibroblasts due to well-developed rough endoplasmic reticulum and Golgi zone

Electron microscopy images

Various images

Colorized SEM

Additional references

Curr Stem Cell Res Ther 2008;3:131, Acta Reumatol Port 2007;32:103

End of Bone Marrow - nonneoplastic > Normal > Osteoblasts

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