Bone Marrow

Bone marrow is the splace between the bone cortex. It contains bone trabeculae and blood vessels. It is the primary site of hematopoiesis in adults.

Bone Marrow Structure

Bone Marrow from diFiore

 

Bone marrow contains vascular sinusoids with a network of reticular cells and fibres in close proximity. The marrow synctitium is designed to provide developing cells with a nutrient-rich environment. Cells lining the sinusoids regulate the exit of cells from the marrow.

 

 

<<PIC of SINUSOIDS>>

 

Hematopoietic Cells

myeloblasts 0-13%

prom 3-12

myelocytes 2-13%

bands/neutrophils 23-45%

eosinophils 0.3-4%

lymphocytes 0-0.4

monocytes

monoblasts 13-38%

 

myeloid : erythroid precursors is normally 2-4 : 1

 

 

Hematopoietic Growth Factors

 

 

 

Bone Marrow Microenvironment

extracellular matrix

The ECM allows attachment of hematopoietic cells and contributes signals controlling proliferation and differentiation. Components include:

ECM also regulates HSC location, facilitating interaction with stromal cells.

 

stromal cells

stromal cells provide physical support for hematopoietic cells and produce growth factors/cell surface proteins that influence differentiation.

 

 

 

 

 

 

Factors Affective Responsiveness