Haematopoiesis Flashcards
Where does haematopoiesis occur in the embryo?
Yoke Sac- 0-10w
Liver- 6- birth (main)
Spleen- Week 12+
Marrow- Week 16+
Where does haematopoiesis occur in the neonate?
Bone marrow- Found in most bone cavities
Liver and spleen if needed
Between birth and maturity where does haematopoiesis occur?
Number of actives sites in bone marrow decreases but retain ability for haematopoiesis
In the adult where does haematopoiesis occur?
Axial skeleton bone marrow Skull Ribs Sternum Pelvis Femoral head Liver and spleen
What are the two types of bone marrow?
Red
Yellow
Describe red bone marrow
Haemopoietically active
Describe yellow bone marrow
Fatty inactive.
How does yellow bone marrow levels vary with age?
Increases with age
What are the three main components of the bone marrow?
Cellular
Connective tissue matrix
Vasculature
What are the cellular components of bone marrow?
Haemopoietic cells
Non-haemopoietic cells- Adipocytes, osteocytes
What is special about the vasculature of the bone marrow?
Large venous sinuses with discontinuous basement membranes.
Why are there fenestrations in the bone marrow vasculature?
Allow new blood cells to exit the marrow
Where can a bone marrow biopsy be taken in an adult?
Iliac crest
Sternum
Where can a bone marrow biopsy be taken in a child?
Tibia
Where does haematopoiesis occur?
Red bone marrow
What can be measured to measure haematopoisis?
Haemopoietic progenitor/stem cell
Mature cells
How do you measure Haemopoietic progenitor/stem cell?
Bone marrow sample and immunophenotyping
Why must Haemopoietic progenitor/stem cell be immunophenotyped?
Because they’re morphologically identical
How do you measure mature cells?
Blood count
Blood film
Describe microenviroment regulation of haematopoiesis
Haempoietic stem cells occupy a ‘niche’ (anatomical site) that provides signals for expansion, differentiation or dormancy
How common are Haematopoetic stem cells?
Uncommon
Describe Haematopoetic stem cells
Morphologically similar
Able to self renew which is lost in later cells
What do haematopietic stem cells progress into?
Multipotent progenitor
How common are Multipotent progenitor?
Uncommon
Describe Multipotent progenitor
Undifferentiated but cannot revert to stem cells.
Morphologically similar.
What do Multipotent progenitor progress to?
Oligolinegal progenitors
How common are Oligolinegal progenitors?
Uncommon
Describe Oligolinegal progenitors
1st stage of differentiation.
Morphologically similar.
Sets off down myeloid or lymphoid route
What is the first stage of differentiation between myeloid and lymphoid?
Oligolinegal progenitors
What do Oligolinegal progenitors differentiate into?
Pronormoblast/Proerythroblast
What do Pronormoblast/Proerythroblast progress into?
Normoblast/erythroblast
What is a ‘blast’?
Nucleated blood cell progenitor
What do normolasts progress into?
Mature cells (reticulocytes etc)
What different types of normoblast are there and what do they progress into?
Megakaryocytes- Platelets
Reticulocytes- RBC
Myelocytes- Neutrophils
What do reticulocytes progress to?
RBC
What do megakaryocyes progress to?
Platelets
What do myelocytes progress to?
Neutrophils
What is the Myeloid:Erythroid ratio?
Ratio of neutrophis and precursors to erythroblasts/reticulocytes (normally 1.5-3.3:1)
What is the normal Myeloid:Erythroid ratio?
1.5-3.3:1
