hematopoiesis (hematology exam 2 topic)

hematopoiesis

formation of blood cells

stem cells

undifferentiated cells that differentiate into specific types of cells (RBC, WBC, etc)

can stem cells renew themselves?

yes, stem cells renew themselves

compartments of hematopoiesis

1. stem cells

2. progenitor cells

3. precursors of specific cell lines

where are stem cells located

stem cells are located in the bone marrow

where are progenitor cells located

progenitor cells are located in the bone marrow

where are precursors of specific cell lines located

precursors are located in the bone marrow and in the blood

which of the three compartments of hematopoiesis are identifiable?

only precursors are morphologically identifiable

types of stem cells

1. uncommitted stem cells

2. hematopoietic stem cells

hematopoietic stem cells

-precursor for RBC, WBC, and platelets

-capable of self-renewal and pluripotency

-morphologically unidentifiable

progenitor cell compartment

-committed to one specific cell line

-form morphologically recognizable cells

-known as CFC or CFU- form colonies of cells in culture (in vitro)

-morphologically unidentifiable

erythropoiesis

formation of red blood cells

origin and development of erythropoiesis

bone marrow

progenitor cells of erythropoiesis

BFU-E and CFU-E

precursor cells of erythropoiesis

-normoblasts (nucleated red cells)

-produced in response to erythropoietin

erythropoietin (EPO)

stimulates the production of red blood cells

identifying stages of erythrocyte maturation

1. cell size and shape:
- immature cells are large and become smaller as they mature

2. cytoplasm staining reaction
- immature NRBC have lots of RNA so they stain intensely blue

3. nuclear/cytoplasmic ratio
- immature NRBC have a big nucleus at first and then it decreases with maturation (and eventually expelled)

4. nuclear staining reaction
-early stages=reddish-purple and as it condenses it becomes dark purple, almost black

5. nuclear chromatin pattern
-early stages it is evenly distributed and you can see nucleoli

normoblastic maturation sequence

1. pronormoblast
2. basophilic normoblast
3. polychromatic normoblast
4. orthochromatic normoblast

distribution of erythroblasts

-quantitative distribution of NRBC in the bone marrow

-distribution of NRBC in the blood

-if any NRBC is seen in differentiation count, they are counted separately

megaloblastic maturation

-type of dyserythropoiesis (production of abnormal erythroid cells)

etiology of megaloblastic maturation

-associated with vitamin B12 or folic acid deficiency

ineffective erythropoiesis

many cells die and undergo phagocytosis in the BM

progenitor cell for megakaryocytes and platelets

CFU-MK

megakaryocytes and platelets

-thrombopoietin regulates production

-progenitors develop through endomitosis

maturation sequence for megakaryocytes and platelets

1) megakaryoblast

2) promegakaryocyte

3)megakaryocyte

4) platelets

neutrophils

-progenitor cell = CFU-GM (shared with monocytes)

neutrophil maturation sequence

1. myeloblast
2. promyelocyte
3. myelocyte
4. metamyelocyte
5. band
6. segmented

(purple=BM, Black=blood)

neutrophilia

-increased

>7.2×10^9/L

neutropenia

-decreased

<2.0×10^9/L

neutrophils are…

bacterial related

neutrophil function

-phagocytosis and destruction of foreign bodies

-chemotaxis= brings neutrophils to site

-opsonization=neutrophil receptors recognize opsonization that potentiate phagocytosis

-degranulation=release the content of granules in other to kill pathogens

morphologic alteration in neutrophils

activated by invading organisms (“reactive changes”)

dohle's bodies

-blue/purple inclusions in cytoplasm

-remnants of ER or ribosomes

-not normal

-not specific

Eosinophil progenitor

- CFU-Eo

origin and development of eosinophils

bone marrow

maturation sequence of eosinophils

1) myeloblast

2) promyelocyte

3) eosinophilic myelocyte

4) eosinophilic metamyelocyte

5) eosinophilic band

6) eosinophil

eosinophil are…..

parasite related

function of eosinophils

-response to foreign pathogens (parasites)

-capable of phagocytosis

origin and development of basophils

Bone marrow

basophils are…..

allergy related

basophil progenitor

CFU-Baso

functions of basophils

-response to foreign proteins

-release of histamine and other mediators

monocyte and macrophage progenitor cells

-CFU-GM (shared with neutrophils)

maturation sequence for monocyte and macrophage

1. myeloblast/monoblast
2. promonocyte
3. monocyte
4. macrophage

(purple=BM, black=blood, Blue= tissue)

monocytes and macrophages are…..

immune related

origin and development of monocytes and macrophages

bone marrow

function of monocyte/macrophage

-phagocytosis

-participation in immunologic reactions

origin and development of lymphocytes

-initially developed in central (primary) lymphoid organs and then further developed in peripheral (secondary) lymphoid tissue.

B-cells= bone marrow
T-Cells= thymus

lymphocytes are…..

viral related

two major populations of lymphocytes

CD4+ (T helpers) and CD8+ (T cytotoxic)

T-cell functions

responsible for cellular immunity

B-cell functions

responsible for humoral immunity

function of lymphocytes

-plasma cells secrete antibodies

-response results in distinctive changes- reactive lymphocytes are formed.

all cellular components are derived from…?

haematopoietic stem cells