Consists of cells that are dividing and include common myeloid progenitors (CMP), GMPs, myeloblasts, promyelocytes, and myelocytes

Consist of cells undergoing nuclear maturation that form the marrow reserve and are available for release: metamyelocytes, band neutrophils, and segmented neutrophils

High N:C ratio (8:1 to 4:1), fine chromatin, no visible granules, slightly basophilic cytoplasm.

Contains up to 20 dispersed primary (azurophilic) granules in the cytoplasm.

Dark chromatin, purple cytoplasm, and more than 20 granules that do not obscure the nucleus

Make up 0% to 3% of nucleated cells in the bone marrow, and measure 14 to 20 μm in diameter

Make up 1% to 5% of nucleated cells and measure 16 to 25 μm in diameter

The nucleus is round to oval, often eccentric, with one to three visible nucleoli; with chromatin clumping around the nuclear edges

First stage of granule production (primary granule/azurophilic granule).

Hof” - A clear zone around the nucleus in normal promyelocytes, absent in malignant promyelocytes, such as those in acute promyelocytic leukemia.

Which stage is the end of proliferative stage?

Make up 6% to 17% of nucleated cells and are 15 to 18 μm in size.

This is the final stage of neutrophil development where cell division (mitosis) occurs.

“Dawn of neutrophilia” This marks the beginning of secondary granule formation showing as pale pink patches of cytoplasm representing these granules.

Comprise 3 to 20% of nucleated marrow cells.

A.k.a. Juvenile cell.

This is the first stage wherein the nucleus is indented (kidney bean-shaped or peanut-shaped).

The synthesis of tertiary granules (gelatinase granules) begins during this stage

9 to 32% of nucleated marrow cells, and 0 to 5% of the nucleated peripheral blood cells.

he nuclear indentation exceeds half the diameter of the nucleus. It becomes “sausage-shaped”.

Secretory granules (secretory vesicles) may begin to be formed during this stage.

A.k.a. Stab cell or Staff cell.

First stage seen normally in peripheral blood

should be included within the neutrophil count and not as a separate category

7 to 30% of nucleated cells in the bone marrow (reserve)

Has the characteristic presence of 2 – 5 nuclear lobes connected by threadlike filaments.

Parasitic infection

This marks the beginning of secondary granule formation showing as pale pink patches of cytoplasm representing these granules

A clear zone around the nucleus in normal promyelocytes, absent in malignant promyelocytes, such as those in acute promyelocytic leukemia

Chromatin of Myeloblast

Chromatin of Promyelocyte

Chromatin of Myelocyte

Chromatin of Metamyelocyte

Chromatin of Bands

Chromatin of Segmented

Myeloblast

Promyelocyte

Myelocyte

Metamyelocyte

Bands

Segmenters

Most common WBC in the normal peripheral blood.

Granulocyte-Monocyte Progenitor (GMP): Common progenitor of neutrophils with monocytes.

Functions: 1. Phagocytosis and destruction of foreign material and microorganisms (major function) 2. Generation of neutrophil extracellular traps (NETs) which are extracellular threadlike structures believed to represent chains of nucleosomes from unfolded nuclear chromatic material (DNA) “NETosis” – describes the unique form of neutrophil cell death that results in the release of NETs.

Secretory function: source of transcobalamin I or R binder protein, necessary for the proper absorption of vitamin B12.

Make up 1 to 3% of nucleated cells in the bone marrow.

This lineage is established through signaling via the cytokines: (1) IL-3 (2) IL-5 (3) GM-CSF

be identified cytochemically because of the presence of Charcot-Leyden crystals protein in their primary granules.

Mature forms display a bilobed nucleus with characteristic refractile, orangered secondary granules.

Functions: Ø Degranulation via: ü Classical exocytosis ü Compound exocytosis ü Piecemeal degranulation ü Cytolysis Ø Immune regulation Ø Mast cell regulation Ø Major Basic Protein (MBP) release, causing mast cell degranulation and cytokine production. Ø Parasitic defense.

Derived from progenitors in the bone marrow and spleen.

1. IL-3-elicited (IgE-dependent) 2. TSLP-elicited (non-IgE-dependent) - Thymic stromal lymphopoietin (TSLP)

Immature forms have round to lobulated nuclei with slightly condensed chromatin, blue cytoplasm, and large blue-black secondary granules.

Mature forms have a lobulated nucleus often obscured by granules, clumped chromatin, and large blue-black granules; a reddish-purple ring may form if granules dissolve during staining.

Functions: Ø Initiation of allergic responses (release of preformed cytokines like IL-4 and IL-13 and inducing IgE production by B cells). Ø Granzyme B production (mediator of allergic inflammation) Ø Retinoic acid production (regulator of immune and resident cells in allergic diseases, induced by mast cells). Ø Angiogenesis (via expression of vascular endothelial growth factor or VEGF).

Not considered to be leukocytes.

Only circulate in the peripheral blood for a brief period on their way to their tissue destinations.

Functions: Ø Allergic response (tissue effector cells) Ø Triggers inflammation without IgE activation. Ø Antigen presentation (differentiation of TH2 cells) Ø Immune regulation Ø Immunologic “gatekeepers” due to their location in mucosal surfaces, acting as barriers.

Have several phenotypic and functional similarities with basophils and eosinophils.

Tissue effector cells of allergic responses and inflammatory reactions.

have round to lobulated nuclei with slightly condensed chromatin, blue cytoplasm, and large blue-black secondary granules.

have a lobulated nucleus often obscured by granules, clumped chromatin, and large blue-black granules; a reddish-purple ring may form if granules dissolve during staining

(M-CSF): the major cytokine responsible for growth and diUerentiation.

Divided into three major groups (T cells, B cells, and NK cells) which function for adaptive immunity, except for NK cells that are part of innate immunity.

They are diUerent from other leukocytes in the following ways: 1) They are not obligate end cells (undergoes mitosis upon stimulation). 2) They recirculate the blood to the tissues, and back. 3) T and B cells are capable of rearranging antigen receptor gene segments. 4) NK and T cells develop and mature outside the bone marrow (thymus).

(3 to 21% of circulating lymphocytes)

(51 to 88% of circulating lymphocytes)

(4 to 29% of circulating lymphocytes)

Downey cells

a.k.a. Plasmacytoid lymphocyte

Turk’s irritation cell

Seen in German Measles.

(a.k.a. Infectious mononucleosis cell

With flared skirt or “fried egg”.

Basophilic cytoplasm that hugs surrounding RBCs, resembling “ballerina skirting

According to the ICSH, the term “reactive” should be used when something is benign, and “abnormal” when it is malignant.

It is very rare in normal bone marrow and difficult to distinguish morphologically from myeloblasts.

Malignant forms are seen in acute monoblastic leukemia.

Larger than neutrophils, slightly immature, and spread out on surfaces

The nucleus is round, oval, or horseshoe shaped.

Promonocytes normally undergo 2 mitotic divisions in ______ hours, producing 4 monocytes.

Nucleus is slightly indented/folded with delicate chromatin, and one visible nucleolus.

Liver macrophage

Lungs macrophage

Brain macrophage

Skin macrophage

Spleen macrophage

Intestine macrophage

Peritoneum macrophage

Bone macrophage

Synovial macrophage

Kidneys macrophage

Reproductive organ

Lymph nodes macrophage

Placental macrophage