Home   Chapter Home   Jobs   Conferences   Fellowships   Books


Bone marrow - nonneoplastic



Reviewers: Dragos Luca, M.D. (see Reviewers page)
Revised: 4 February 2013, last major update September 2012
Copyright: (c) 2001-2013, PathologyOutlines.com, Inc.
PubMed Search: osteoclast
Broken links/comments: click here or email CommentsPathOut@gmail.com, subject=bonemarrowosteoclasts


● Cells derived from hematopoietic progenitor cells involved in bone resorption, primarily due to remodeling and not calcium homeostasis
● Along endosteal surface of bony trabeculae (reside in Howship lacunae) or along margins in marrow smears
● Common in children (active bone remodelling); in adults associated with metabolic or neoplastic diseases
● Some overlapping immunophenotypic features with monocytes / macrophages
● Relatively recently identified osteoclast colony stimulating factor and transcription factors involved in osteoclastogenesis
● Activated by parathyroid hormone and by cytokines RANKL and macrophage colony-stimulating factor (Arthritis Res Ther 2006;8:201)
● Osteoclasts use their ruffled borders (with villous extensions) to bind to matrix adhesion proteins, produce resorption pits / bays (shallow concavities) called Howship’s lacunae
● Plasma membrane forms a seal with bone; osteoclast acidifies extracellular area, which solubilizes the mineral and releases enzymes which dissolve the matrix


Left to right: cross-section; bone resorptive cycle; osteoclast differentiation

Micro description

● Very large (up to 100 microns), multinucleated (2-12 nuclei) giant cells associated with bone surface
● Abundant, blue-purple-pale pink cytoplasm containing many fine, red-purple granules
● Also contain bone sand in the cytoplasm
● Multiple, relatively uniform but widely separated nuclei, each with one nucleolus and dense chromatin
● Generally, less mature osteoclasts have basophilic cytoplasm and mature forms have brightly eosinophilic cytoplasm

Micro images



Very large cell with multiple nuclei with distinct nucleoli, cytoplasm has coarse azurophilic granules

Positive stains

● CD13, CD31, CD51 (Histochemistry 1991;96:169)
● CD53, CD54, CD61, CD63, CD68, CD115, acid phosphatase, microphthalmia transcription factor and TRAP

Electron microscopy description

● Numerous mitochondria, rare lysosomes
● Ruffled edge in area of cell membrane is associated with bone resorption

Electron microscopy images

Left: osteoclast resorbing bone

Additional references

Keio J Med 2003;52:1, Wikipedia, Anat Embryol (Berl) 1984;170:51

End of Bone Marrow - nonneoplastic > Normal > Osteoclasts

This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.

All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions (click here for other contact information).