Clinical Pathology Chapter 6

• Bone Marrow
• Marrow is present in the medullary cavities of bones

In extreme cases areas such as the liver and spleen can produce blood cells

in the Bone Marrow

In the lymph nodes

In young animals marrow in all bones is active and highly cellular

as animals age, the amount of active marrow in the long bones decreases and is replaced with fat. Marrow remains active in flat bones (ribs, sternum, pelvis, and skull)

Rubriblast- prorubicyte-rubricyte- metarubicyte (nucleated Reb Blood Cell)-retiulocyte-RBC (erthrocyte)

Myeloblast- promyelocyte- myelocyte-metamyelocyte-granulocyte (neutrophil, basophil, eosinophil)

monoblast- monocyte

• Lymphoblast (T or B) - Lymphocyte (T or B)
• B cells are produced in the Bone marrow.

The precursors of T cells are also produced in the bone marrow but leave the bone marrow and mature in the thymus

Megakaryoblast- megakaryocyte-multiple platelets

• Non-regenerative anemia of undetermined cause
• Abnormal cells are found on the blood smear
• Culture in cases of osteomyelitis

Inflammation of the bone

• Proximal Humerus
• Proximal femur
• Wing of the ilium

• Rosenthal bone marrow aspiration needle
• jamshidi needle is used to get bone marrow core for biopsy

Preform a naked eye inspection of the slides to select the smear containing the best particles (marrow fragments)

• Slide Cellularity: With 10x objective survey the particles whether they are normocellular, hypocellular or hypercellular. In many cases one may just obtain blood (blood tap) or nothing at all (dry tap) When
• not enough bone marrow fluid is collected in a bone marrow aspiration.
• Under these conditions the aspirate has to be repeated, or a bone marrow biopsy has to be performed.

• Normocellular- normal amounts and types of cells
• Hypocellular- containing less than the normal number of cells
• Hypercellular- containing more than the normal number of cells

• Myeloid to Erythroid ratio
• Use the 10x or 40x objective. The number of large, pale staining cells with dispersed chromatin (myeloid cell)
• should be compared to the number of dark staining cells with clumped chromatin (ie. erythroid cells). This is a quick, but reliable method of determining the M:E ratio.. Normal ratios very from 1:1 to 3:1

suggests an origin in the bone marrow or spinal cord, or a resemblance to the marrow or spinal cord

Cell that will give rise to erythrocytes

Maturation of erythroid and myeloid series: In normal bone marrow 80% of the nucleated series should be rubricytes and metarubricytes. In the myeloid series, 80% of cells should be metamyelocytes, bands, and segmented Neutrophils. Blast cells should be less than 5% of the neutrophils. Blast cells should be less than 5 % of the total. If the greater than 30% of cells are blasts cells, a hemic neoplasia (ie. leukemia) is probably present.

• Erthlichiosis- Tick born
• FeLV -Feline Leukemia Virus
• FIP Virus- Feline infectious peritonitis

Chemotherapy and radiation

• ITP- Immune Mediated Thrombocytopenia
• IMHA- IMMUNE MEDIATED HEMOLYTIC ANEMIA or “IMHA” (FORMERLY KNOWN AS AUTOIMMUNE HEMOLYTIC ANEMIA or “AIHA”

• The componants of marrow are being "crowded out by abnormal cells. Most often due to neoplasia of one or more of the cells in the normally exist in the marrow.
• Myeloproliferative disease (cancer)

Hemostasis is the process the body uses to stop the flow of blood when the vascular system is damaged.

• Vascular Spasms
• Platelet Formation
• Clot formation or coagulation

Platelets (thrombocyte) are formed in the bone marrow and are cell fragments derived from megakaryocytes.

• to Form the initial plug at the site of hemorrage
• Release numerous active chemicals which initiate the clotting process