Bone Marrow Flashcards
What is hematopoiesis?
Process by which immature precursor cells develop into mature blood cells
What cell gives rise to all mature blood cells (erythrocytes, monocytes, lymphocytes, thrombocytes, granulocytes)?
Pluripotent stem cells (CD34+)
What are the morphological stages of blood cell development?
- -blast
- pro-
- -cyte
- Meta-
- Mature blood cell
What are the morphological stages of erythrocyte development starting from stem cells?
Myeloid stem cells –> rubriblast –> Prorubricyte –> rubricyte –> metarubricyte –> reticulocyte –> erythrocyte
What are the morphological stages of platelet (thrombocyte) development from stem cells?
Myeloid stem cells –> Megakaryoblast –> Promegakaryocyte –> Megakaryocyte –> thrombocytes (platelets)
What are the morphological stages of eosinophils, basophils, neutrophils starting from stem cells?
stem cell –> Myeloblast –> promyelocyte –> myelocyte –> metamyelocyte –> Stab (band) cells –> eosinophil, basophil, neutrophil
What are the morphological stages of development of a macrophage?
Monoblast –> promonocyte –> monocyte –> macrophage
Starting from lymphoid stem cells, describe the morphological stages of development of lymphocytes.
Lymphoblast –> prolymphocyte –> T & B lymphocytes –> T cells & plasma cells
What cells are normally found in blood?
reticulocytes, erythrocytes, platelets, eosinophils, basophils, neutrophils, monocytes, T & B lymphocytes
When would you see undifferentiated cells in blood?
in an unhealthy animal
-Blast cells are the most recognizable of each cell development. Why?
They are bigger and have a nucleolus
If you see a -blast with a nucleolus in the peripheral blood, what might this be a sign of?
Cancer
What are interleukins?
Protein cytokines working w/ colony stimulating factors (CSF) to stimulate cell lines to proliferate, differentiate, and activate.
What are the main interleukins that relate to hematology?
1, 3, 5, 6, 7, 11, 15
What does renal erythropoietin (EPO) do?
stimulates RBC production
What does hepatic thrombopoietin (TPO) do?
stimulates platelet production
How is hematopoiesis regulated?
By GFs, CSFs, ILs, Hormones
IL 1 and 6 are common in the regulation of what cells?
WBCs
What are the sites of hematopoiesis in mammal embryos?
Extra-embryonic –> blood islands of the yolk sac
Along the aorta
What are the sites of hematopoiesis in a mammal fetus?
liver, spleen, bone marrow cavity
What are the sites of hematopoiesis at birth?
BM, spleen
Liver as needed
What are the sites of hematopoiesis as an adult mammal?
BM of the skull, ribs, sternum, vertebrae, pelvis, proximal femur, humerus
In an adult mammal, where does extramedullary hematopoiesis (EMH) occur?
Spleen, liver (if extreme/chronic)
Where in the bone marrow does hematopoiesis take place?
Extravascular space
High activity of the bone marrow can be demonstrated by…
its daily output of mature blood cells
Other than pumping out new cells, what else does the bone marrow partake in?
- Removal of aged & defective erythrocytes
- Differentiation of B lymphocytes
- Site of numerous plasma cells
- Removing HJB
What does the hematopoietic microenvironment look like?
- Lattice-like scaffolding
- Stroma composed of fibroblasts, myofibroblasts, adipocytes, endothelial cells, macrophages, ECM
What does the stroma of bone marrow do?
supports & provides humoral (cytokines) & cellular (adhesion proteins, receptors) signaling vital to normal bone marrow growth, regulation, & fxn
The structure of precursor cells change as it goes from…
making more protein to less
A cell making lots of protein has…
- nucleus-containing active, dispersed chromatin for active transcription
- many large nucleoli for ribosomal RNA synthesis and assembly
- more cytoplasmic ribosomes thus more basophilic cytoplasm
- Highly developed Golgi apparatus causing an acentric nucleus
Cells making less protein have…
- Condensed, clumped chromatin
- Smaller, fewer nucleoli
- Fewer ribosomes –> appears more acidophilic
- Smaller Golgi & nucleus is more centrally located
What cells are part of normal erythropoiesis?
Rubriblast, prorubricyte, basophilic rubtricyte, polychromatophilic rubricyte, metarubricyte, reticulocyte
The kidney is the site of production of…
EPO (erythropoietin)
Bone Marrow has what two compartments?
Vascular and extravascular compartments
Where in the extravascular space does hematopoiesis take place?
- Stroma of reticular CT
- Parenchyma of developing blood cells, plasma cells, macrophages, and fat cells
What determines high activity of the bone marrow?
The daily output of mature blood cells, and the large numbers of lymphocytes and monocytes
Bone marrow is the site for what other important activities?
- removal of aged & defective erythrocytes
- differentiation of B lymphocytes
- site of numerous plasma cells
- removal of HJBs
What is the stroma of the hematopoietic environment made of?
fibroblasts, myofibroblasts, adipocytes, endothelial cells, macrophages, ECM
What does the stroma of the hematopoietic microenvironment do?
supports & provides humoral (cytokines) & cellular (adhesion proteins & receptors) signaling vital to normal BM growth, regulation, & fxn
A cell making lots of protein has…
- a nucleus w/ active, dispersed chromatin
- many large nucleoli
- more cytoplasmic ribosomes (more basophilic)
- Highly-developed Golgi apparatus occupying the cytoplasm causing an acentric nucleus
Cells making less protein have…
- condensed or clumped chromatin
- smaller, fewer nucleoli
- fewer ribosomes
- smaller Golgi, more centrally located nucleus
What stage of erythrocyte development is this?
Prorubricyte
What stage of erythrocyte development is this?
Basophilic rubricyte
What stage of WBC development is this?
Myeloblast
What stage of WBC development is this?
Myelocyte
This image shows some of the developmental stages of…
WBCs
When is a bone marrow biopsy indicated?
- unexplained, persistent decrease in cell type
- Bi- or Pancytopenia
- nRBC’s in absence of marked regenerative response
- persistent increases in cell types
- Suspect myeloproliferation/ leukemia - atypical or blasts
- Evaluation of infectious Leishmaniasis, histoplasmosis
- Differentiation, diagnosis, and staging of cancers
What are some risks of a bone marrow biopsy?
sepsis, hemorrhage
What cancers can be determined and evaluated by a bone marrow biopsy?
Lymphoma
Leukemia
Histiocytic neoplasia
multiple myeloma
mast cell neoplasia
metastatic carcinoma
What are some sites in the skeleton that are best for taking bone marrow biopsies?
- iliac crest
- proximal humerus/femur
- sternum
- rib
What is the best place to take a bone marrow biopsy in a young animal?
iliac crest
What is the best place to take a bone marrow biopsy in an older animal?
sternum
in order to assess the cellularity of a bone marrow sample microscopically, what will you need?
spicules of marrow
Cellularity of bone marrow is assessed from the relative amount of ____ ____ as a ___
adipose tissue, %
What amount of fat is considered normal when assessing cellularity of bone marrow?
30-70%
When interpreting cellularity of bone marrow, what aspect of the patient must be taken into account?
the patient’s age
The cellularity of bone marrow can be classified into what three groups?
Hypocellular
normocellular
hypercellular
Myelofibrosis causes…
bone marrow failure secondary to replacement of normal marrow elements with fibrous tissue
What species get myelofibrosis?
dogs, cats, humans, goats
Myelofibrosis can be primary or secondary to…
malignancies
IMHA
whole body irradiation
congenital anaemias
