Hematopoiesis

Question 1

Romanovsky Type Blood Stains (basic)

Answer 1

methylene blue - stains RNA-rich cytoplasm heavenly blue (esp if ribosomes)
azure B - stains DNA/GAG-rich nuclei or cytoplasmic granules of basophils/lysosomes crimson

Question 2

Romanovsky Type Blood Stains (acidic)

Answer 2

eosin - general stain for PRO (red-pink)

-Hb of RBC and granules of eosinophils

Question 3

hematopoetic organs

Answer 3

bone marrow (RBC, granulocytes, monocytes)
lymphoid organs (lymphocytes)
fetal (liver)

Question 4

monophyletic theory of hematopoiesis

Answer 4

all blood cells are derived from common pluripotential (hematopoietic) stem cell

Question 5

stages of granulopoiesis

Answer 5

development of granulocytes (neutrophils, eosinophils, basopihls)
myeloblast–> promyelocyte–> myelocyte–> metamyelocyte–> band cell–> mature cell
-first 4 only in bone marrow, last 2 in normal peripheral blood

Question 6

polyphyletic theory

Answer 6

each type of blood cell arises from own stem cell (not widely held theory)

Question 7

blast cell appearance

Answer 7

all blood cells start out like this (RBC, WBC, platelet)

• large cell, 10-15 microns
• large euchromatic nucleus
• several nucleili
• high nucleocytoplasmic ratio
• numerous ribosomes (creates methylene blue stain)
• no cytoplasmic granules

Question 8

what changes a blast must undergo to become a neutrophil

Answer 8

• condense nuclear chromatin (disappearance of nucleoli)
• lobulate nucleus
• appearance of cytoplasmic granules (primary/secondary)
• decrease in cytoplasmic basophilia

Question 9

neutrophil promyelocyte

Answer 9

2nd step after blast; capable of mitosis

• same size as blast
• spherical nucleus with slight chromatin condensation
• nucleoli observed
• growing appearance of primary (azurophilic) granules and primary lysozomes (w/ hydrolytic enzymes

Question 10

neutrophil myelocyte

Answer 10

3rd step, after promyelocyte; losing ability to make DNA/RNA

• nucleus is round/oval and more heterochromatic (azure B); more condensed, less basophilic
• appearance of secondary (specific) granules w/ lysozyme/lactoferrin (kill bacteria)
• -cause cytoplasmic color change from heavenly blue to salmon pink

Question 11

neutrophil metamyelocyte

Answer 11

4th step, after myelocyte; no longer able to make DNA/RNA, or mitosis

• kidney-shaped nucleus (beginning of lobulation), more condensed
• no basophilic cytoplasm, and higher ratio of small specific : large azurophilic granules
• salmon-pink cytoplasm

Question 12

neutrophil band cell

Answer 12

5th step, after metamyelocyte; when indentation exceeds 1/2 diameter of nucleus (looks like C or S)

• chromatin condensed, and cytoplasm looks mature
• found in peripheral blood (1-5% total leukocytes)

Question 13

clinical use of % of neutrophil band cells

Answer 13

provides rough indication of rate of neutrophil production in patient
-“shift to the left” - increase in % of bands in buffy coat indicates stress ins placed on bone marrow to create more neutrophils

Question 14

definitive marker of band to mature neutrophil

Answer 14

when segments between lobes have become thin heterochromatic filaments, and nuclei completely lobed

Question 15

kinetics of neutrophil (and other granulocyte) production

Answer 15

9-14 days (blast to mature), mostly in bone marrow
1 day in peripheral blood (circulating and marginating, exchanging between them)
5 days in surrounding tissue (diapedesis)
total life span = 15-20 days

Question 16

differences in eosinophilic development

Answer 16

specific granules are are larger, almost black when first appear
-become pink-red as maturation continues

Question 17

differences in basophilic development

Answer 17

specific granules are much bigger, stain purple in smears

Question 18

distribution of granulocytes

Answer 18

marrow granulocytic reserve (MGR) - cells in bone marrow
total granulocytes in peripheral circulation (TBGP) - granulocytes in peripheral circulation
MCR is 10X TBGP

Question 19

sites of hematopoiesis

Answer 19

flat bones of body

• sternum
• vertebrae
• ribs
• clavicles
• pelvis
• skull

Question 20

components of red blood marrow

Answer 20

small blood vessels
discontinuous sinusoids
hematopoietic cords
hematopoietic stem cell niche
stem cells for other tissues, so can make unrejected cells

Question 21

hematopoetic stem cell niche (in RBM)

Answer 21

interactive structural unit that nurtures stem cells and facilitates their activity (critical for development)

• localized supporting cells, ECM PRO, soluble factors (showing stem cells not randomly distributed)
• found in association with spongy bone (OC/OB, etc.)
• alterations may cause myeloproliferative disease (preleukemic condition)

Question 22

what blasts have to do to become RBCs

Answer 22

decrease cell volume
disappearance of nucleoli/nucleus
increase heterochromatin
decrease cytoplasmic basophilia, increase eosinophilia (hemoglobin)

Question 23

stages of erythropoiesis

Answer 23

blast–> basophilic erythroblast–> polychromatophilic erythroblast–> normoblast–> reticulocyte–> orthochromatic erythroblast–> RBC

Question 24

basophilic erythroblast (BEB)

Answer 24

2nd stage, after blast

• cell/nucleus smaller than blast
• checkerboard chromatin nucleus, loss of nucleolus
• basophilic cytoplasm (b/c increase free ribosomes for globin production)
• lasts 1-2 days, divides 1-2 times

Question 25

polychromatic erythroblast (PCE)

Answer 25

3rd stage, after BEB - cell/nucleus smaller than BEB - further chromatin condensation - gradual shift from intense basophilia to intense acidophilia (b/c increase hemoglobin and decrease ribosome) so double-staining - lasts 3 days, divides 3-4 times

Question 26

normoblast (NB)

Answer 26

4th stage, after PCE (no more mitosis; terminal) - cell/nucleus smaller than PCE - totally heterochromatic - cytoplasm mostly pink, slight blue

Question 27

fates of normoblasts

Answer 27

80%: extrude nucleus, retain ribosomes --> reticulocyte | 20%: lose residual RNA before nuclear extrusion --> orthochromatic erythroblast

Question 28

orthochromatic erythroblast

Answer 28

same color as RBC, just nucleated - small heterochromatic nucleus, bright eosinophilic cytoplasm - not present in normal peripheral blood (nucleus pops out before circulation)

Question 29

maturation time for RBCs

Answer 29

``` 1-2 days: BEB 3 days: PCE 3 days: NB --> reticulocyte transition 1 day: reticulocyte --> RBC transition total 8-9 days ```

Question 30

erythropoietin

Answer 30

glycoPRO hormone - made in kidney (via endothelial cells) - increases rate of mitosis (in blasts, BEB, PCE) - increases RNA synthesis in developing RBCs (for Hb) - lessens degree of brain damage after stroke, and stimulated by hypoxia

Question 31

reticular cells

Answer 31

large cells with cytoplasmic processes (mainly phagocytosis of extruded nuclei) - lots of ingested material in cytoplasm - large, pale staining nucleus - plays trophic role in RBC maturation

Question 32

erythroblastic island

Answer 32

developing RBCs that cluster around reticular cells in bone marrow, so that they can phagocytose nuclei

Question 33

plasma cells

Answer 33

basophilic cytoplasm negative image of Golgi eccentically placed nucleus "clock face" chromatin

Question 34

megakaryoblast

Answer 34

large cell 40-50 um diameter large/spherical nucleus b/c polyploid homogenous basophilic cytoplasm

Question 35

megakaryocyte

Answer 35

even larger cell (up to 150 um diameter) lobulated nucleus increases poidy to 32-64 n (endomitosis) eosinophilic cytoplasm, w/ azurophilic granules invaginations of plasma membrane throughout cytoplasm -forms demarcation channels -results in partitioning of cytoplasmic fragments to form platelets -platelets enter discontinuous sinusoids in bone marrow

Question 36

proplatelet model of platelet production

Answer 36

1. extension of psuedopods 2. formation of long extensions (proplatelets) 3. platelets released from ends of proplatelets 4. demarcation channels are membrane reservoir

Question 37

kinetics of platelet formation

Answer 37

4-5 days: megakaryocyte maturation 10 days: platelets circulate destroyed in spleen/liver, with functional mRNAs (may mitosis?)

Question 38

what blasts must do to become lymphocytes

Answer 38

``` decrease cell size condense chromatin disappear nuclei acquire cell surface receptors migrate to thymus (T) or stay in bone marrow (B) for differentiation ```

Question 39

kinetics of monocyte differentiation

Answer 39

2-3 days: formation in bone marrow 1-2 days: circulation 1-3 months: in tissue as macrophages