PART 3- THIRD LEARNING Flashcards
The bone marrow produces
platelets, erythrocytes, granulocytes (neutrophils, eosinophils, and basophils), monocytes and probably the bursa equivalent of B lymphocytes.
The status of the bone marrow cellular activity is reflected in
peripheral blood cell counts
The requirement for direct marrow examination the living animal is not a common practice but needs to be considered when there are:
- Inexplicable peripheral blood changes
- In cases of suspected myeloproliferative disorders
- Inexplicable peripheral blood changes such as:
a. The presence of cells with abnormal or atypical morphology
b. Inappropriate response to an anemia or infection;
c. The development of unexplained anemia and or leukopenia.
Growing animals show active red marrow which is replaced by
replaced by fat tissue as the animal mature
In old animals, active (red) marrow is restricted to the
flat bones and the endosteal area of long bones
Although the marrow respond to heavy demands following infectious insults, in some chronic infectious cases, the spleen, liver, adrenal and other areas where there are foci of primitive mesenchymal cells, production of hematopoietic cells occur at these sites and the process
extramedullary hematopoiesis
hematopoietic cells
Erythroid and myeloid precursors
undergo differentiation and maturation in marrow spaces before their release into vascular sinusoids.
erythroid and myeloid precursors
are entered b hematopoietic cells via diapedesis or proplatelet shearing
vascular sinusoids
structurally support the marrow
trabecular bone
produces trabecular bone
ostoeblasts
sit on a basal lamina and separate the vascular sinusoids lumens from marrow hematopoietic and stroma cells.
endothelial cells
line vascular sinusoids and release cytoplasmic fragments (platelets) into sinusoidal lumens.
megakaryocytes
provide structural and metabolic support to hematopoietic cells
stromal cells
constitute 25% to 75% of the total marrow space. the proportion of adipocytes increases with age.
adipocytes
mechanism of disease in bone marrow and blood cells
BONE MARROW
hypoplasia
hyperplasia
dysplasia
aplasia
neoplasia
myelophthisis (fibrosis, metastatic neoplasia)
necrosis
inflammation
BLOOD CELLS:
increased destruction
hemorrhage (erythrocytes)
consumption
neoplasia
altered distribution
abnormal function
- increased production of various cell lines which occurs frequently in response to demands by, or changes in the other parts of the body.
1) Hyperplasia
is used where the increased production is at the expense of the other cell lines.
MYELOID METAPLASIA
refers to the general reduction in the amount of cells produced in the bone marrow that are in circulation.
2) Pancytopenia
The response is generally that of marrow aplasia and may be caused by such factors
as irradiation, chemical and bacterial toxin and some drugs.
Causes of marrow depression include viral diseases such as
parvovirus, enteric infection of dogs and cats and feline leukemia virus infection, and Erhlichiosis.
is a term used to describe the metastasis of neoplastic cells to the bone marrow
5) MYELOPTHISIS
Commonly accepted hypotheses include:
a. Direct damage to mitotically active cells by various agents, and
b. failure of the microcirculation of bone marrow.
Drugs such as
phenylbutazone, and estrogenic drugs can also cause marrow aplasia
Necrosis of bone marrow result
pancytopenia
is the abnormal proliferation of fibroblast in the marrow cavity
4) MYELOFIBROSIS
that causes bone marrow depression include Bracken fern poisoning.
Phytotoxicities
Two hypotheses for this condition include:
a. As part of repair process following injury to bone marrow;
b. Fibroblastic proliferation as a consequence of a chronic hemolytic anemia
Myelofibrosis often produces characteristic morphological alterations in peripheral blood and include poikilocytosis, with the presence of
poikilocytosis, with the presence of elliptocytes, schizocytes and dacryocytes.
refers to a peripheral disorder associated with faulty maturation, development, and cell division involving one or all of the marrow cell lines
- Myelodysplasia, dysmyelopoiesis
The defect is basically the presence of abnormal stem cells in the marrow which may or may not progress into neoplasia.
- Myelodysplasia, dysmyelopoiesis
- refers to the abnormal proliferation of marrow cell lines and may include myelodysplasia and neoplasia
- Myeloproliferative disorder
Infiltration of neoplastic cells into other tissues can occur with enlargement of the liver and spleen ()
often being the most prominent feature
(hepatomegaly and splenomegaly)
are usually characterized by the presence of leukemia
Myeproliferative neoplasms
(presence in blood of large number of neoplastic cells of myeloid origin)
leukemia
The designation of such neoplasm referable to the cell type or the major cell stage involve (e.g.
(e.g. granulocytic leukemia, myeloblastic leukemia, myelocytic leukemia).
is the major site of blood formation (when marrow becomes fully developed).
Bone marrow
is a valuable diagnostic tool in the differential diagnosis of diseases characterized by alterations in the peripheral blood
Bone marrow examination
I. INDICATIONS AND LIMITATIONS
A. Indications
1) For confirmatory diagnosis of leukemia 2) Differential diagnosis of anemia e.g. megaloblastic anemia, nutritional anemia, normoblastic anemia
3) To confirm blood count findings, especially leukopenia, nonregenerative anemia, thrombocytopenia
the needle is advanced into the marrow cavity with stylet locked in place.
klima needle
B. Limitations
1) Difficulty in obtaining samples - usually contaminated with peripheral blood.
2) Adequate experience in bone marrow examination is required.
Stylet is then removed and syringe used to aspirate the marrow.
the stylet is in place for advancement through soft tissue and cortex.
Jamshidi neeele
on reaching the bone marrow , the needle is advanced without the stylet to create a core sample.
jamshini needle
is used to expel the sample into formalin.
probe (hooked)
C. Sites for collection
anterolateral part; this is the best source of bone marrow samples for dogs and cats.
1) humerus
sites for dogs and cats
2) iliac crest
11th or 12th;site for cattle, horses
4) rib
1st or 2nd sternebra; sites for cattle, horses, sheep
3) sternum
trochanteric fossa; the most preferred site for cats.
5) femur
III. PREPARATION OF ASPIRATED MATERIAL FOR EXAMINATION;
A. Bone marrow smear
- slide film method
- coverslip method
METHOD:
Bone marrow aspirate is mixed with EDTA and sieved in order to get only the marrow granules. The granules are washed with saline, embedded in 2% agar and fixed with 10% formalin.
- Agar-gel method
Methods
1. Bone marrow aspirate is allowed to clot and placed in
10% formalin for sectioning.
C. Stains
Wright’s, Wright-Giemsa, May-Grunwald-Giemsa
A. Degree of Cellularity
1. Hypoplasia may be
a) generalized
b) erythroid
- Hyperplasia
a) erythroid
b) granulocytic
c) megakaryocytic
B. Presence of all cell series include the ff.
- granulocytic
- erythrocytic
- megakaryocytic
C. Sequence of development
Mature cell types should outnumber
the immature forms
Developmental stages:
- Granulocytic series:
Myeloblast
progranulocyte
myelocyte
metamyelocyte
band cell
segmented granulocyte
- neutrophils
- eosinophils
- basophils
- Lymphocytic Series
lymphoblast
prolymphocyte
lymphocyte
- Monocytic Series
monoblast
promonocyte
monocyte
- Erythrocytic Series
rubriblast
prorubricyte
rubricyte
metarubricyte
reticulocyte
erythrocyte (RBCs)
- Thrombocytic series
megakaryoblast
promegakaryocyte
megakaryocyte
calculated by dividing the total number of granulocytes by the total number of granulocytes by the number of nucleated erythrocytes
M:E Ratio (myeloid: erythroid)
M:E Ratio
(myeloid: erythroid)
-in normal animals, the M:E ratio is
1:1
VI. Specific Findings in Anemia, Inflammation and Neoplasia:
Anemia
1. decreased M:E ratio, predominance of metarubricytes, punctate basophilia
- regenerative