Hematopathology

This is the appearance of normal bone marrow at medium magnification. Note the presence of megakaryocytes, erythroid islands, and granulocytic precursors. This marrow is taken from the posterior iliac crest in a middle aged person, so it is about 50% cellular, with fatty tissue admixed with the marrow elements.

• This is the appearance of normal bone marrow at high magnification. Note the presence of megakaryocytes, erythroid islands, and granulocytic precursors. This marrow is taken from the posterior iliac crest in a middle aged person, so it is about 50% cellular, with steatocytes admixed with the marrow elements.

• This is the appearance of normal bone marrow smear at high magnification. Note the presence of megakaryocytes, erythroid precursors, and granulocytic precursors.

Early intermediate late

Proerythoblast

Erythroblasts or normoblasts

Reticulocyte

Mature RBC

Proerythoblast

Normoblasts Intermediate Late

Red Cell precursors (in Red Cell precursors (in marrow)marrow)

Microscopical Features:

•Reduction in the cell size.•Loss of nucleoli.•Clumping of nuclear chromatin.•Hemoglobinization of the cytoplasm.•Loss of nuclei.

Stages of Maturation of the Granulocytic Series

In the bone marrow

Bone marrow

Blood

Microscopical Features:

•Reduction in the cell size.•Loss of nucleoli.•Granulation of cytoplasm ( primary and secondary).•Nuclear segmentation.

Blood leucocyte morphology

1.Neutrophils• They are also known as polymorphonuclear

leukocytes.

• They have a multilobed nucleus which may appear like multiple nuclei, hence the name polymorphonuclear leukocyte.

• The cytoplasm may look transparent because of fine granules that are faintly pink in color.

Function of Neutrophil

• Neutrophils defend against bacterial or fungal infection and other very small inflammatory processes that are usually first responders to microbial infection & they are are very active in phagocytosing bacteria & are present in large amount in the pus of wounds.

• Their activity and death in large numbers forms pus.

• These cells are not able to renew their lysosomes used in digesting microbes and die after having phagocytosed a few pathogens

2.Eosinophil• Generally their nucleus is bi-lobed. The cytoplasm is full of

granules which assume a characteristic pink-orange color with eosin stain.

Function:

• Eosinophils primarily deal with parasitic infections .

• Eosinophils are also the predominant inflammatory cells in allergic reactions.

3. Basophils

• The nucleus is bi- or tri-lobed, but it is hard to see because of the number of coarse granules which hide it.

• They are characterised by their large blue granules.

Function:• Basophils are chiefly responsible for allergic and

antigen response by releasing the chemical histamine causing inflammation.

4. Lymphocyte

• Lymphocytes are much more common in the lymphatic system. • Lymphocytes are distinguished by having a deeply staining nucleus

which may be eccentric in location.• B cells make antibodies that bind to pathogens to enable their

destruction.• CD4+ (helper) T cells co-ordinate the immune response and are

important in the defense against intracellular bacteria. In acute HIV infection, these T cells are the main index to identify the individual's immune system activity.

• CD8+ cytotoxic T cells are able to kill virus-infected and tumor cells. CD8+ cells are also another index to identify human's immune activity.

• It has a relatively small amount of cytoplasm.

Monocyte 5.• They have the kidney shaped nucleus and are

typically agranulated. They also possess abundant cytoplasm.

Function:• Monocytes share the "vacuum cleaner"

(phagocytosis) function of neutrophils

• Monocytes eventually leave the bloodstream to become tissue macrophages which remove dead cell debris as well as attacking microorganisms.

Megakaryocyte : the precursor of Platelets in the marrow

Microscopical Features:

•Increased cell size.•Lobulation of the nuclei.•Cytoplasmic granulation.

• The red blood cells here are normal, happy RBC's. They have a zone of central pallor about 1/3 the size of the RBC. The RBC's demonstrate minimal variation in size (anisocytosis) and shape (poikilocytosis). A few small blue platelets are seen. In the center of the field are a band neutrophil on the left and a segmented neutrophil on the right.

• A normal mature lymphocyte is seen on the left compared to a segmented PMN on the right. An RBC is seen to be about 2/3 the size of a normal lymphocyte.

• Here is a monocyte. It is slightly larger than a lymphocyte and has a folded nucleus. Monocytes can migrate out of the bloodstream and become tissue macrophages under the influence of cytokines. Note the many small smudgy blue platelets between the RBC's

• In the center of the field is an eosinophil with a bilobed nucleus and numerous reddish granules in the cytoplasm. Just underneath it is a small lymphocyte. Eosinophils can increase with allergic reactions and with parasitic infestations

• There is a basophil in the center of the field which has a lobed nucleus (like PMN's) and numerous coarse, dark blue granules in the cytoplasm. They are infrequent in a normal peripheral blood smear, and their significance is uncertain. A band neutrophil is seen on the left, and a large, activated lymphocyte on the right.

White Blood Cells