Nadia Goodwin & Missy Walker Blood and Bone Marrow Histology SSN November 18, 2004 Presented by: Nadia Goodwin & Missy Walker

Formed Elements of the Blood

Peripheral Blood: Erythrocytes RBCs constitute the largest number of cells in the blood Biconcave discs NO NUCLEUS Contain Hemoglobin

Peripheral Blood: Platelets Derived from Megakaryocytes in bone marrow – formed from small bits of Megakaryocyte cytoplasm Function in blood clotting

Peripheral Blood: Leukocytes GRANULOCYTES Neutrophils Basophils Eosinophils AGRANULOCYTES Lymphocytes (T and B cells) Monocytes (Macrophages)

Peripheral Blood: Leukocytes GRANULOCYTES Neutrophils Basophils Eosinophils

Granulocytes: Neutrophils Most numerous WBC in blood Multilobed nucleus Granules: Azurophilic granules Specific granules Function 1st wave of cells in acute inflammation; can phagocytose bacteria

Granulocytes: Basophils Rare! Lobulated nucleus often obscured by granules Dark Blue Granules Hydrolytic enzymes, heparin sulfate, histamine, SRS Function Role in hypersensitivity and anaphylaxis

Granulocytes: Eosinophils Bilobed nucleus Bright pink Granules Arginine rich major basic protein, peroxidase, histaminase, arylsulfatase Function: Important in allergic rxns, parasitic infections, and phagocytosis of Ab-Ag complexes

Agranulocytes: Monocytes Largest WBCs in blood smear Migrate through blood to the tissues; once in tissues they differentiate into phagocytes (macrophages)

Agranulocytes: Lymphocytes About size of RBCs Function Main functional cells of adaptive immune system T cells B cells

Questions Which of the following cell types would be expected to be increased in number with a bacterial infection? Viral? Parasitic?

RBC Development Watch for trends!

Proerythroblast Biggest in lineage Large central nucleus with one or two nucleoli Basophilic cytoplasm b/c ribosomes Look for Golgi ghost

Basophilic Erythroblast Smaller than proerythroblast Checkerboard nucleus (heterochromatic) Intense basophilia (lots of ribosomes!)

Proerythroblast vs Basophilic Erythroblast

Polychromatophilic Erythroblast Smaller than basophilic erythroblast Smaller intensely heterochromatic nucleus Purple/lilac cytoplasm mix of basophilia from ribosomes and growing eosinophilia from hemoglobin LAST MITOTIC STAGE!

Normoblast Smaller than polychromatophilic erythroblast Small, compact, intensely staining nucleus that is getting ready to be extruded Eosinophilic cytoplasm due to abundant hemoglobin

Reticulocyte Immature RBC that has polyribosomes Appear as polychrom-atophilic erythrocyte on blood smear When stained with a special (supravital) stain  Reticulocyte

Erythrocyte Smallest Eosinophilic due to hemoglobin NO NUCLEUS!

Erythropoiesis

Development of Granulocytes

What are the Granulocytes? These are cells of the immune system (White Blood Cells) that contain vesicles. The vesicle contents vary among cell lines and stain differently. Neutrophils (polymorphonuclear or PMN cells) Eosinophils Basophils

Trend of Development Larger to smaller Azure granules to specific granules Round nucleus to altered shape nucleus Granulocyte Lineage: Myeloblast → Promyelocyte → Myelocyte → Metamyelocyte → Band → Granulocyte (Erythroid: Proerythroblast →Basophilic erythroblast → Polychromatophilic erythroblast → Normoblast → Reticulocyte → Erythrocyte)

Myeloblast Prominent nucleoli

PROmyelocyte Details Golgi ghost Can’t distinguish type of granulocyte yet Eccentric nucleus Don’t confuse with proerythroblast or basophilic erythroblasts

Myelocyte Last stage in which mitosis can occur Begin to see who’s a neutrophil, who’s an eosinophil (who’s a basophil) Golgi ghost

Neutrophilic Myelocyte vs Eosinophilic Myelocyte

METAmyelocyte nucleus changing shape, not spherical Soooo . . . No more mitosis

Band Cell Immature granulocyte Elongated nucleus of nearly uniform width; horseshoe/U-shaped

Finally . . .

Myeloblast – no granules capable of mitosis Promyelocyte – azurophilic granules Mylocyte – specific granules Metamylocyte – specifc granules nucleus changes shape Band cell – (PMN only) specific granules Mature Granulocyte – specific granules

Compare what you see . . .

Megakaryocyte Huge Platelets form from invaginations of this Multilobular nucleus

Megakaryocyte

Don’t Worry, Be Happy!