II. Physiology
- Bone Marrow produces lymphocytic progenitor cells
- Lymphoblasts form in marrow, divide to Prolymphocytes
- Prolymphocytes develop into 2 separate cell lines
- B-Lymphocytes develop in Bone Marrow
- T-Lymphocytes develop in Thymus
- Bone Marrow produces three stem cell myeloid lines
- Erythroblasts (Initial cell known as Proerythroblast)
- Develop into erythrocytes (Erythropoiesis)
- Myeloblasts (Granuloblasts)
- Represent 75% of nucleated cells in marrow
- Develop into Promyelocyte and then Granulocyte
- Characteristics
- Evenly distributed fine chromatin
- Multiple nucleoli
- Basophilic cytoplasm (non-granular)
- Megakaryocyte (Megalokaryocyte)
- Giant cell with multi-lobulated nucleus in marrow
- Releases mature Blood Platelets from cytoplasm
- Erythroblasts (Initial cell known as Proerythroblast)
III. Background
- Minimum of 500 cells must be counted
- Sample staining
- Wright Stain or
- May-Grunwald-Giemsa Stain
IV. Normal Bone Marrow Examination Findings
- Fat to Cell Ratio
- Child under age 10 years: 10% fat to 90% cells
- Adult: 30% - 70% fat to 70% - 30% cells
- Myeloid to Erythroid ratio: 3 to 1 ratio
- Erythroid Cells: 18 to 39% of marrow nucleated cells
- Megakaryocytes: 0.5 to 2% of nucleated cells in marrow
-
Lymphocytes: 11 to 23% of nucleated cells in marrow
- T-Lymphocyte to B-Lymphocyte ratio: 3 to 1
- Plasma Cells: 0.4 to 3.9% of nucleated cells in marrow
- Myeloid Cells: 60-75% of nucleated cells in marrow
- Neutrophilic series: 49 to 65%
- Eosinophilic series: 1.2 to 5.3%
- Basophilic series and Mast Cells: <0.2%
V. References
- Lee (1999) Wintrobe's Hematology, Lippincott, p. 23-25