B8 +D1 Bone Marrow
Bone Marrow:
- Bone marrow is a complex specialised connective tissue found in the central cavities of many of our bones
- It is the site of blood cell formation, or haematopoiesis
- Bone marrow contains a variety of cell populations:
- These form a 3D structural framework to support the differentiating blood cells
- In addition, they release growth factors which promote haematopoiesis
- These are common in bone marrow
- In inactive bone marrow, known as yellow marrow, adipose cells occupy most of the marrow cavity
- These include the haematopoetic stem cells and also the various stages in the differentiation of all the types of blood cell
- It is very difficult to distinguish each of the different differentiation stages
- However, the very large (>100 microns) megakaryocyte can easily be distinguished - this is the cell that buds off platelets
- Bone marrow that is actively producing blood cells is known as red marrow
- In addition there are many large diameter thin walled blood sinuses
- These bring in nutrients and oxygen to support haematopoiesis and also provide the route out for newly formed blood cells
Stromal cells
Adipose (fat) cells
Haematopoetic cells
Bone Marrow - 2:
- In this tissue section of bone marrow several structures are labelled:
- Megakaryocyte (the cells that bud off platelets)
- Adipose cells
- Thin walled blood sinus (these contain circulating blood)
- In between the three types of labelled structure is located a mixture of stromal cells (support cells) and cells at various stages of haematopoiesis
