W1 Lec 5- The bone marrow Flashcards
What is hemapoiesis?
formation of blood cells
Define granulopoiesis
formation of granules
What is the formation of platelets called?
megakaryopoiesis or
thrombopoiesis
Blood cell synthesis not included in hematopoiesis
lymphopoiesis
Where does hemapoiesis take place?
bone marrow of the spongy bone (callus)
What is the blood supply in the bone called?
Sinusoid
Lists stages of RBC maturation
-Erythroblast»Normoblast»Polychromasia (mature erythocyte)
List stages of Neutrophil maturation
Blast»Promyelocyte»myelocyte»metamyelocyte»Band cell»mature neutrophil
Explains the process from megakaryocyte to platelets
- Megakaryocyte has a large nucleus with granules all over the cytoplasm
- The large nucleus is a result of endomitosis
- Pseudopod formation
- Megakaryocyte extend long cytoplasmic protrusions called proplatelets into the bone marrow sinusoids
- Extended proplatelets undergo fragmantation, which is the breakdown of proplatelets into smaller platelets
- As the proplatelets fragment, these granules are released into the blood stream forming the platelets we recognise.
Other cells in the bone marrow
lymphocytes, plasma cells,
macrophages, fat cells
What is marrow cellularity?
Is the composition and density of cells within the bone marrow
These cells see an increase in numbers with age, within the bone marrow. The average adult marrow cellularity (% haemopoiesis)
is 40 - 60 %
Adipocytes
Why are there fat spaces in the marrow?
-Those fats are stored in the form of triglyceride within the marrow. They serve as energy reserves in periods of increased energy demand, or decreased food intake
- Bone health: Play a role in bone remodelling and metabolism.
How do we diagnose disease in the bone marrow?
- Bone marow biopsy
What is the best site for marrow biopsy?
- iliac crest
What are the samples obtained for bone marrow biopsy?
- Bone marrow aspirate (liquid bone marrow obtained containing blood cells, using a needle)
- Bone marrow trephine (bone marrow tissue is obtained using a large needle- done to diagnose haematological disoders such as leukemias, lymphomas, myeloma)
What are the uses of the aspirate?
- Provide cells for cytological examination – cells spread
on a slide, stained and examined microscopically. enables “morphological” study of cells - Provide anticoagulated specimens for: flow cytometry
cytogenetics, culture – TB, bacterial, fungal - Provide uncoagulated specimen for DNA PCR and FISH
What are the uses of trephine biopsy?
Used to see the:
- ARCHITECTURE of the bone marrow rather than individual cells
- granulomas
- infiltrating neoplasms e.g.
lymphoma, carcinoma
- marrow necrosis
- fibrosis
What is trephine imprint or touch Prep?
A techniques that involves pressing the cut surface of the bone marrow core into a slide (can capture cellular material even if there is no fluid obtained through aspiration)
The technique is used in the case of dry tap; when the needle does not yield an adequate sample of the bone marrow fluid.
Why go for trephine imprint?
- It can be done routinely.
- Very helpful if the marrow is infiltrated with tumour
- Helpful in cases of dry tap
