BLOOD and BONE MARROW
OVERVIEW
PERIPHERAL BLOOD SMEARS:
only contains mature cells (no precursors)
cell types:
erythrocytes
platelets
leukocytes:
granulocytes: neutrophils, basophils, eosinophils
agranulocytes: lymphocytes, monocytes (macrophages)
PERIPHERAL BLOOD SMEARS
1. erythrocyte
largest proportion of cells in the blood
biconcave discs (7-8 µm)
lack nucleus and cellular organelles
composed of hemoglobin (carries O2 and CO2)
2. neutrophil (polymorphonuclear granulocyte)
50-70% of leuko’s in peripheral blood
diameter = 10-12 µm (larger than RBC)
3-5 lobed nucleus stains deep purple
pale cytoplasm
small azure/light blue/violet granules
specific granules (bacteriocidal agents: lysozyme, alkaline phosphatases)
azurophilic granules (peroxidase, lysosomal enzymes)
function: acute inflammation (exit circulation to site of injury, phagocytose pathogen, granules fuse with phagosome to
destroy pathogen)
3. basophil
rare, hard to find (less than 1% of leuko’s)
diameter = 8-14 µm
lobulated nucleus, obscured by granules
dark blue specific granules of varying sizes
contain hydrolytic enzymes, heparin sulfate, histamine, slow reacting substance, SRS
act like tissue mast cells, bind antigen specific IgE, exposure to antigen releases vasoactive substances from granules,
leads to inflammation
4. eosinophil
2-4% of leuko’s
diameter 10-14 µm
bilobed nucleus
bright pink eosinophilic granules of uniform sizes
contain arginine rich major basic protein, peroxidase, histaminase, arylr-sulfatase
important in allergic reactions, parasitic infections, and phagocytosis of antibody-antigen complexes
5. monocytes
3-8% of leuko’s
diameter 9-18 µm (usually larger than PMN’s)
kidney shaped nucleus, less compact nucleus than PMN
pale, basophilic cytoplasm without specific granules, but do contain azurophilic lysosomes
exit circulation to tissues, differentiate into phagocytes (macrophage, osteoclast, alveolar macrophage, etc)
differentiated monocytes function in phagocytosis & antigen presentation to lymphocytes
6. lymphocytes
20-40% of leuko’s
diameter = 6-12 µm
intensely staining, slightly indented spherical nucleus
thin, pale blue rim of cytoplasm WITHOUT granules
B cells & T cells are indistinguishable
B cells: function in antibody production, carry Ig on plasma membrane which recognize antigen
T cells: function in cell mediated immunity, destroy virally infected cells, provide help to B cells
ERYTHROID SERIES
PROERYTHROBLAST
- relatively large cell 12-15µm in diameter
- large, central, spherical nucleus with one or two nucleoli
- cytoplasm: moderately basophilic (blue) due to ribosomes
- look for an unstained region of cytoplasm=Golgi ghost
BASOPHILIC ERYTHROBLAST
- smaller than proerythroblast
- checkerboard nucleus (heterochromatic and smaller)
- intense basophilia (blue) due to lots of free ribosomes
POLYCHROMATOPHILIC ERYTHROBLAST
- smaller than basophilic erythroblast
- smaller intensely heterochromatic nucleus
- purple/lilac cytoplasm due to combo of basophilia from ribosomes and eosinophilia from increasing
amount of hemoglobin
- LAST MITOTIC STAGE
NORMOBLAST
- smaller than polychromatophilic erythroblast
- small, compact, intensely staining nucleus; getting ready to extrude the nucleus
- eosinophilic cytoplasm (abundant hemoglobin); NOTE: the color of a normoblast is close to the
normal pinkish color of the mature erythrocyte
ERYTHROCYTE
- smallest (7-8 µm)
- NO NUCLEUS
- Acidophilic (pink)
- Reticulocytes are immature erythrocytes that still retain some basophilia
TRENDS
Immature ⇒⇒Mature
Basophilic ⇒⇒ Eosinophilic
Large euchromatic nuclei ⇒ heterochromatic ⇒ pyknotic ⇒ no nucleus
All precursors have the word “blast” in their name