Hematopoiesis: Formation of Blood Cells

• Hematopoiesis is also referred to as hemopoiesis
• It’s the continuous, regulated process of renewal, proliferation, differentiation, and maturation of blood cell lines
• Results in the formation, development, and specialization of all functional blood cells that are released from the bone marrow into the circulation

Sites of Hematopoiesis

• In the fetus:
• Takes place in the yolk sac during months 0-2
• Takes place in the liver and spleen during months 2-7 (until 2 weeks after birth)
• Takes place in the bone marrow (BM) during months 5-9
• In infants:
• BM→ results in Medullary Hemopoiesis
• Occurs in all bones
• In adults:
• Takes place in the BM of the central skeleton and proximal ends of long bones
• Occurs in the vertebra, sternum, ribs, skull, sacrum, pelvis & proximal ends of femur & humorous, and this is called Medullary Hematopoiesis
• In Infancy blood cells are produced within all of the bone marrow
• Active bone marrow is red, inactive is yellow
• During Childhood, for the first 4 years of life, nearly all the marrow cavities contain red active marrow with very few fat cells
• Then, there's a gradual replacement of active marrow by fatty tissue throughout the long bones
• In adults, active marrow is confined to the central skeleton, including the skull, sternum, ribs, vertebrae, pelvis & proximal ends of femur & humerus
• Note: Fatty marrow may change back to red active marrow if necessary

Phases of Hematopoiesis

• Mesoblastic Phase:
• Takes place in the yolk sac
• Hepatic Phase:
• Occurs in the liver
• Occurs in the spleen
• Myeloid Phase:
• Occurs in red bone marrow

Mesoblastic Phase

• Definition: Takes place in the Yolk sac (blood islands)
• Primitive erythroblasts are the main products formed during the mesoblastic phase
• Hemoglobin (Hb) produced: Gower I & II, Portland

Hepatic Phase

• Begins during weeks 4-5 of gestation
• Ends 1-2 weeks after birth
• Primary location: Liver ((2-7) months of gestation)
• Has a secondary location in the spleen
• Results in Definitive hematopoiesis (RBC's, WBC's)
• Produces Hemoglobin- Hb-F

Medullary Phase

• Starts during the 5th month of gestation
• Continues throughout life
• Bone marrow is the only location in the body this process takes place after the 2nd week of birth
• Products: The various stages of maturation can be seen in all three lineages
• Hemoglobin produced: Hb-A, Hb-A2, Hb-F

Extramedullary Hematopoiesis

• When liver & spleen begin to produce blood cells in adults
• Leads to blood cell production outside the bone marrow (B.M) (i.e., liver & spleen) in adults
• Occurs when indications cause an increase in blood cells production exceeding B.M capacity
• Leads to the expansion of hematopoiesis down the long bones & even extramedullary

Hematopoietic Hierarchy

• Hematopoietic stem cell has CD34+, CD38-
• Hematopoietic stem cell has self-renewal capacity
• It differentiates into various cell lines
• Resembles a small/medium sized lymphocyte
• Committed progenitor cell:
• Gives rise to descendents of restricted development to a specific line
• Is morphologically unrecognized
• Blast cell:
• Is 1st recognizable cell in lineage
• Is mitotically active
• Mature cell:
• Is functionally active
• Is mitotically inactive

Anatomy of the Red Bone Marrow

• Forms a suitable environment for stem cells to survive, grow & develop
• Composed of stromal cells, microvascular network
• Stromal cells include:
• Adipocytes (Fat cells)
• Fibroblasts
• Endothelial cells & macrophages
• Osteoclasts & osteoblasts
• Reticulum cells
• Red Bone Marrow: Hematopoietic cells
• Yellow Bone Marrow: Fat / Adipose tissue

Regulation of Hematopoiesis

• There should be a balance between blood cell production (Hematopoiesis) and normal cell death (Apoptosis) except at times of requirement
• Apoptosis: Programmed cell death
• Hematopoiesis is regulated by Growth Factors/Hormones

Hematopoietic Growth Factors

• Substances similar to hormones, and are also be called cytokines & interleukins (IL)
• Glycoproteins are present in minute amounts (picograms)
• Usually affect more than one lineage
• Usually act on stem, progenitor cells & on mature cells
• Usually show synergistic or additive interactions with other growth factors
• Biological effects of GFs are mediated by specific receptors on target cells

General Morphologic Changes during Cell Maturation

• Decreased Cell diameter
• Decreased nuclear diameter
• Loss of nucleoli
• Condensation of Nuclear chromatin
• Decreased basophilia in the cytoplasm
• Loss of the Nucleus (Erythrocytes)

Hematopoiesis gives rise to

• Erythropoiesis (Erythrocytes)
• Granulopoiesis (Granulocytic Leucocytes)
• Megakaryopoiesis (Thrombocytes)
• Lymphopoiesis (Lymphocytes)

Erythropoiesis

• A regulated process of RBCs production within the Bone Marrow (BM)
• Erythron: The entire mass of mature & immature RBC's in the body
• There is a balance between RBC's production & destruction

Process of Erythropoiesis

• Includes Proliferation during which there is a division of immature cells to produce increased numbers of more mature cells
• Followed by Maturation that involves The development of cells through early, intermediate & late stages
• 3 Points of Control of Erythropoiesis:
• Control of the self-replication of progenitor cells
• Control of the movement of mature cells from bone marrow into blood
• Feedback control on cell production

Stages in the Development of Erythrocytes

• Begins with the Megakaryocyte Erythroid Progenitor (ΜΕΡ)
• Followed by Proerythroblast
• Early Erythroblast
• Intermediate Erythroblast
• Late Erythroblast
• Nuclear Extrusion
• Reticulocyte
• Ends with the formation of RBCs

Proerythroblast

• These are the earliest recognizable erythroid cell in the bone marrow
• Size (12 - 20 μm)
• Round nucleus centrally placed within the cell with visible nucleoli & chromatin strands that are dispersed
• Cytoplasm is usually only a narrow rim around the large nucleus, deep blue (RNA) when stained by Romanowsky dyes

Early Erythroblast/Early Normoblast/Basophilic Normoblast

• Slightly smaller than Pronormoblast
• Size: 10 - 16 µm in diameter
• Nucleus: occupies less of the cell & does not contain nucleoli with more condense chromatin
• Cytoplasm: predominant color is blue (RNA) with little pinkish color
• This is a sign that Hb, which stains pink, is being produced & the RNA & protein synthetic apparatus is being lost
• Polychromatic Normoblast / Intermediate Normoblast
• Smaller than basophilic normoblast but with twice the amount of Hb
• Cell size: 8 - 14 µm in diameter
• Nucleus is smaller & denser, nuclear chromatin is condensed
• Cytoplasm shows a polychromatic staining reaction with a predominate pinkish color

Orthochromatic Normoblast/Nucleated RBC

• 8 to 10 mm in diameter
• Nucleus is eccentric, small, solid & blue black with clumped chromatin
• Cytoplasm is predominantly pinkish (Hb)
• Mitochondria are no longer evident
• Normally not seen in PB

Polychromatophilic Erythrocyte/Reticulocyte

• Young RBC containing some fine basophilic material which gives it a bluish stain (RNA remnant)
• Size: 8 - 10 µm in diameter
• Nucleus is extruded
• Retics are released to blood, there it needs (1-2) days before maturation
• Normally, rarely found in PB
• Retics can be stained with a supravital stain as brilliant cresyl blue or new methylene blue, by which reminant RNA is stained blue & appear as filaments or granules

Mature Erythrocytes

• Biconcave disc with circular outline
• (7 - 8) µm in diameter
• (1.5 - 2.5) µm in thickness
• Stained pink (Hb)
• Paler central area (2-3) µm
• No nucleus or mitochondria
• Life span: 120 days
• Each pronormoblast divides into 14 – 16 mature RBCS
• RBCs production takes about 10 days from the pluripotent stem cell to the mature RBCs
• From reticulocyte to fully mature RBCs, approximately 1 - 2 days

Regulation of Erythropoiesis

• Erythropoiesis is regulated by the hormone erythropoietin (EPO)→ by increasing the number of progenitor cells committed to erythropoiesis
• The human erythropoietin gene is located on chromosome 7
• EPO is produced by (90% kidney & 10% by the liver)
• Oxygen level in kidney's tissues controls EPO production.
• When O2 supply to renal tissue falls, EPO levels increase
• When O2 supply to renal tissues increases, EPO levels falls
• Erythropoietin plays a critical role in RBCs production, other factors are also necessary for the formation of fully functioning cells which include:
• Metals: iron & cobalt
• Vitamins: Vitamin B12, folic acid & vitamin (B6 pyridoxine)
• Hormones: Stem Cell Factor (SCF), IL-3 & androgens
• Amino acids: for protein production

Reticuloendothelial System (R.E.S.)

• R.E.S. consists of the spleen, liver & bone marrow
• RE cells "macrophages" destroy RBCs by process of phagocytosis
• Called "extravascular Destruction" of the red cell.
• On average, 1% of the body's RBCs are destroyed & replaced each day This means that 2.5 million cells are replaced each day by bone marrow
• Ineffective Erythropoiesis is normally when some of immature RBC's don't develop normally in BM (1-15%)
• So, they don't reach maturity & circulation
• They are removed by macrophages in BM
• In ineffective erythropoiesis these cells (not developing into mature RBC's) abnormally increase > 15%

Hemoglobin

• Three RBC components and structures essential for survival and function:
• HEMOGLOBIN
• RBC CELL MEMBRANE
• RBC METABOLISM

Structure of Hemoglobin

• Hemoglobin: Protein molecule in RBCs that transports oxygen from lungs to body's tissues & returns carbon dioxide from tissues to lungs
• Hemoglobin is abbreviated as Hb or Hgb
• Hb is a conjugated protein metal-protein/ chromo-protein
• Its spherical (globular) & water-soluble molecule.
• Its concentration within RBCs is around (MCHC)= 34 g/dl.
• Its molecular weight is 64,450 Da
• Each RBC contains about 640 million Hb molecules
• Hb is the main component of RBCs (predominant protein in the cytoplasm)
• It is the functional unit of RBCs; as a vehicle for O2 transport in the body

One Hemoglobin molecule is composed of:

• 4 Globin chains→ 2 alpha & 2 non-alpha globin chains
• 2 dimers, each has 2 polypeptide chains (1 alpha &1 non alpha)
• 4 Heme groups→ each one locates at the centre of each globin chain
• Heme structure consists of: Protoporphyrin IX which inludes: A ring of C, H & N atoms One atom of iron in ferrous state (Fe+2).
• Protoporphyrin + iron → Ferroprotoporphyrin Each heme ring is a protoporphyrin ring with ferrous (Fe+2) iron at its center
• It is the non-protein part of Hb.
• Heme is synthesized in the mitochondria of developing nucleated RBCs
• Thus, cannot be produced in mature RBCs. Each heme group can combine to one O2 molecule
• Fe+2, which is the O2 binding site, coordinates with four nitrogens at the center of the ring, which all lie in one plane.
• Heme component of RBCs renders blood red Heme is widely distributed in the body- found throughout the body: Myoglobin (muscle protein) Enzyme systems Cytochromes (cell respiration)
• Summary: Non-protein part of Hb "Heme": Protoporphyrin ring structure Iron atom (Fe+2) at centre of ring Formed in mitochondria of nucleated RBCs

Structure of Globin

• Globin is the protein portion of Hb.
• There are six types of globin chains (α, β, γ, δ, ε and ζ)
• These types can be divided into:
• a -globin chains (α & ζ):
• Contain 141 amino acids
• Alpha & zeta
• Non a -globin chains (β, γ, δ and ɛ)→
• Contain 146 amino acids
• Beta, gamma, delta, epsilon
• Globins are formed by the ribosomes of the RBCs

Biosynthesis of Hemoglobin includes:

• Biosynthesis of heme

• Biosynthesis of globin

• Hemoglobin assembly

• O Biosynthesis of Heme

• Occurs in the bone marrow

• Mitochondria of RBCs precursors are the main sites of protoporphyrin ring synthesis Mature RBCs can not make Heme

• First & last steps take place in mitochondria.

• Intermediate steps take place in cytoplasm.

• Iron is supplied from circulating transferrin.

• Each protoporphyrin IX binds to Fe+2 to form heme

Biosynthesis of Globin includes:

• Six structural genes control the synthesis of the six globin chains:
• a (4 genes) & ζ (2 genes) occur in Chromosome 16
• (β, δ, ε 2 genes each) & (γ 4 genes) occur in Chromosome 11 Occurs in the: Formed by ribosomes within the developing RBCs & reticulocyte Globin is a protein. Its synthesis requires the same components & follows the same mechanism as any other protein in the body Different globin chains are produced independently & then combine with one another to produce different Hb types., so Certain embryonic Hbs are usually only present in yolk sac erythroblasts and globin genes are arranged on chromosomes in the order in which they are activated during the different stages of development

Types of Hemoglobin in Humans

Hb composition in RBCs differs, depending on gestation or postnatal age In the Embryo during the first twelve weeks after conception: Gower, 1 (ζ282) (Zeta 2, Epsilon 2) Gower 2 (α282) (Alpha 2, Epsilon 2) Portland (ζ2Y2) (Zeta 2, Gamma 2) In the Fetus: Hb F (a2Y2)(alpha 2, Gamma 2) In adults: Hb A (α2β2)- (Alpha 2, Beta 2), (96 -98%) Hb A2 (α282)- (Alpha 2, Delta 2), (1.5 – 3.2%) Hb F (a2Y2)- (alpha 2, Gamma 2), (0.5-0.8%)

Types of Globin

• ζ and ɛ genes normally appear only during the first 3 months of gestation.
• These two chains with a & y chains are constituents of embryonic Hbs
• The change in Hb types is due to changes in the activation & inactivation or switching of the globin genes with development progressing from: ζ το a-gene on chr 16 ε to δ, γ or genes on chr 11
• globin gene is expressed at a low level in early fetal life, but main switch to Hb A
• Occurs 3 to 6 months after birth when synthesis of gamma chain is largely replaced by beta chain
• Exactly how this 'switch' occurs is not fully understood

Assembly of Hemoglobin

• Each globin binds one heme
• a-chain & non-a-chain combine → two dimers
• Two identical dimers combine → 1 tetramer
• The combination of 2 alpha with 2 non-alpha along with 4 hemes can form: Hb A→ Is the Predominant Hb in postnatal life Hb A₂→δ globins are insufficiently expressed, so small amount of HbA2 is found in RBCS Hb F Its not evenly distributed among the RBC, it's present in few RBCs called F cells
• A globin chain contains a heme ring enclosed within a deep "heme pocket" Heme pocket provides a hydrophobic environment that protects heme molecules It is important that no water enters heme pocket or the ferrous atom (Fe+2) contained within heme becomes oxidized to a ferric (Fe+3) atom This oxidized form of Hb is called met-hemoglobin, with the ferric atom which is unable to transport O2 FUNCTIONS OF HEMOGLOBIN
• The functional unit of RBCs; as a vehicle for O2 transport in the body Red blood cells deliver oxygen to the body’s tissues Red blood cells pick up carbon dioxide that the body produces in order for it to be exhaled, acting as a waste-removal system

Problems that could impact hemoglobin resulting from:

• Substitution of internal & external amino acids e.g. Sickle cell Hb S
• Reduced production of globin chains, can cause Thalassemia syndromes Problems with heme synthesis- deficiencies of enzymes on the synthetic pathway of heme lead to an excess of porphyrins in the body, also know as genetic disorders called Porphyrias.
• Increased breakdown of hemoglobin can cause Hemolytic disorders
• Minor amounts of Hb A is modified after translation
• Hb A₁ can form glycated Hb→ Hb + sugar
• Results from post synthetic, non enzymatic reactions that attach various sugars with amino groups of the globin chains of Hb A
• The most common form: glycated Hb
• Glucose is added to the B-chains of Hb A
• 4-6 % :Normal range of Hb A is in HbA1c
• In uncontrolled DM, Hb A₁c is increased
• Tested in the chemistry lab to diagnose DM

Hemoglobin Derivatives result from acquired Hb variants whose structures have been modified by drugs or environmental chemicals are: Abnormal Hb forms. Heme is altered. Globin chains unaffected Are nonfunctional Can cause abnormal symptoms with different severity.: Met-Hb (Hi) Sulf-Hb Carboxy-Hb

Methemoglobin

• Is the oxidation of Ferrous (Fe+2) to Ferric (Fe+3) Hb state resulting in the inability to carry O2
• Normally found in the body: 0.5-3% What's needed to reduce met-Hb: Met-Hb reductase & NADPH Methemoglobinemia: ↑ RBC's met-Hb levels Hi > 30% causes cyanosis (bluish skin) & hypoxia Hi > 60% is rare & fatal

Sulfhemoglobin

• Results from the oxidation of Hb by adding sulfur (S) atom to each heme molecule from exposure to certain drugs or chemicals, is the Fe+2 form, & has affinity to O₂
• The presence of excessive sulf-Hb in blood known as Sulfhemoglobinemia causes cyanosis

Carboxyhemoglobin

• Hb bound to CO < 1% range (non smokers) 5% range (smokers)
• Increased affinity to CO (200x affinity to O2), a condition known as Carboxyhemoglobinemia causes Hypoxia and can be a “Silent killer”

Hemoglobin Measurement

• Blood Hb concentration [Hb] is the most important parameter of the CBC test.
• Crucial diagnostic value of anemia and reference intervals for Hb are: For Men: 13 - 17 g/dL For Female: 12 - 15 g/dL In Newborns: 16.5 - 21.5 g/dL Note:
  • Individuals living at high altitudes have slightly higher levels of Hb
• [Hb] could be measured in labs by:

1. Automated (autoanalyzer) CBC
2. Manually (Cyan-methemoglobin spectrophotometric method)

Investigating types off Hemoglobin

Using Hemoglobin Electrophoresis: Note that various globins differ in the charge per molecule

• So, in Hb electrophoresis, under the influence of electric field, Hb can be separated & differentiated Red Blood Cell Membrane

Mature RBC's Properties

Mature RBC is a biconcave disc-shaped cell with of all the substances necessary for the transport of O₂ to the tissues and contains gases, substances passing through and allows glucose & other essential nutrients to pass in.

• The membrane surrounding the cell is a very flexible & elastic envelope allowing the RBC to to change its shape and resist pressures as it circulats through small vessels for roughly 120 days as sustain itself by not making new enzymes or proteins and having no nucleus These membranes have 2 main structural and functional features: Composed mainly of lipids & proteins
• Cytoplasm composed entirely of water (63%) & protein as the predominant component

The RBC Cytoplasm is comprised of:

Hemoglobin an iron containing red pigment that is the O2-carrying protein of the blood. 2,3 diphosphoglycerate (2,3-DPG) A molecule that helps Hb bind & release O2 Enzymes & energy providing molecules assist with keeping the cell membrane & the Hb healthy.

• RBC PLASMA MEMBRANE
  • In normal people, RBCs live for about 120 days. The RBC plasma membrane are able to provide the ability to stretch & twist but return to normal shape many times during its lifetime, while allowing gases & other molecules to pass into & out of the cell through it’s two-layered layer of lipid molecules a "lipid billeted" The Double lipid layey consists of: Antigens Proteins Integral proteins contain sialic acid (negatively charged substance) causing: It gives RBC's negative charge Leading the RBC's to repel each other in the circulation→(zeta potential). The movement of cholesterol within the membrane lipid→ allows the membrane to bends When excess cholesterol accumulates, the membrane loses flexibility causing the normal biconcave disk becoming thinner & forms target cells. If cholesterol is removed from the membrane the cell loses flexibility & takes up a spherical shape forming spherocytes If other molecules are inserted into the outer layer of lipid molecules, the membrane is pulled inwards in one direction & stomatocytes are formed If other molecules are inserted into the inner layer of lipid molecules, the membrane is pushed outwards & small spikes form on the external surface of the cell, making cells like these are called ecchinocytes or acanthocytes The internal elastic protein network has considerable ability to deform (change shape) Spectrin molecules are joined together & attached to the membrane proteins & lipid bilayer by physiochemical bonds that allow changes in shape provided that the surface area remains constant If the surface area is increased by stress or the bonds between proteins are chemically changed, the shape change can become permanent This makes the cell less elastic & likely to be broken or fragmented to form schistocytes
• Increased surface area or chemical change (oxidation)= Permanent change and cell cannot return to previous shape

RBC Metabolic Pathways

 - anaerobic glycolysis converts glucose into pyruvate, generating ATP for energy, particularly in RBCs, which lack internal energy stores

• Glucose enters RBCs for via for Glut-1 by facilitated diffusion and generating an ATP Yield- A total of four ATP molecules are produced per glucose yielding a net gain of two ATP after initial investment.

Anaerobic Glycolysis Phases:

Phase 1 Involves glucose phosphorylation, isomerization, and diphosphorylation to form fructose 1,6-bisphosphate (F1,6-BP) by enzymes: Hexokinase is for Phosphorylates glucose, consuming 1 ATP Glucose-6-phosphate Isomerase is for Convert glucose-6-phosphate to fructose-6-phosphate 6-Phosphofructokinase is for Phosphorylates fructose-6-phosphate to F1,6-BP, consuming another ATP The output is F1,6-BP which consumed of total of 2 ATP molecules. Phase 2 converts glyceraldehyde-3-phosphate (G3P) to 3-phosphoglycerate (3-PG) by enzymes of: Glyceraldehyde-3-phosphate Dehydrogenase (G3PD) used in oxidizes G3P to 1,3-bisphosphoglycerate (1,3-BPG), reducing NAD to NADH Phosphoglycerate Kinase Outcome: 3-PG is produced, and a net of 2 ATP is generated Phase 3 converts 3-PG to pyruvate using Phosphoglycerate to Isomerize 3-PG to 2-phosphoglycerate (2-PG) Enolase which Convet 2-PG to phosphoenolpyruvate (PEP) Pyruvate Kinase (PK) is used to converts PEP to pyruvate and produces 2 ATP PK Regulation Activity is enhanced by high levels of F1,6-BP Outcome: Pyruvate is produced, which can either diffuse from the cell or be converted to lactate by lactate dehydrogenase (LDH),regenerating NAD+

Other Processes impacting Glocolysis

• Glycolysis Diversion Pathways (Shunts):
• Three alternate pathways, called diversions or shunts, branch from the glycolytic pathway.
• The three diversions: Hexose monophosphate pathway Methemoglobin reductase pathway Rapoport-Luebering pathway Hexose Monophosphate shunt Also known as pentose phosphate shunt. Utilizes 10% of glucose in RBC. Glucose-6-phosphate is converted to 6-PG by Glucose-6-phosphate dehydrogenase enzyme (G6PD) Generates reduced form of NADPH is important to support: Convert glutathione (GSSG) to reduced glutathione (GSH) Converting H2O2 into water Protecting RBCs from oxidative damage protecting Hb & other membrane proteins from oxidation (keeps SH group intact) Supporting minor role of Met-Hb reduction

Luebering-Rapoport Shunt (LRS)

• Its a side arm in the EMP.
• It generates 2,3-DPG: Forms deoxy-Hb. Hb affinity to O2. It Regulates O2 affinity to Hb in RBCs. ⬆ O₂ delivery to tissues.

Methemoglobin Reductase Pathway Heme iron is frequently exposed to oxygen and peroxide, which can oxidize it from the ferrous (Fe2+) to the ferric (Fe³+) state, resulting in methemoglobin. The Hexose Monophosphate Pathway (HMP) helps or supports preventing of hemoglobin oxidation, by reducing peroxide, but it cannot reverse methemoglobin once it forms. Though NADPH can reduce methemoglobin, this process is slow without additional support. The role of Cytochrome b5 Reductase an eznyme also known as methemoglobin reductase, enhances the reduction of methemoglobin by using electrons from NADH. It serves as an intermediate electron carrier to convert ferric iron back to the ferrous state. With Cytochrome b5 accounting for over 65% of the RBC's capacity to reduce methemoglobin, thus maintaining effective oxygen transport

Leucopeisis

• The introduction to Leukocytes that is a category of cellular blood elements also ≈ white Blood cells (Leuko: white / cyte: cell) It’s leukocytes get their name from the white buffy coat obtained upon centrifugation of whole blood and leukocytes are nucleated cells (typical eukaryotic cells)

• Is the production & development of leukocytes with the main function of WBCs as an immune defense mechanism Five Different Types of Leukocytes in the Peripheral Blood

• These include Neutrophil @ 50% to 70% Lymphocyte @ 20% to 40% Monocyte of 2% to 11%, with the Eosinophil of 1% to 4% as well as the Basophil at 0% to 2%

• White blood cells are broadly classified into 2 types that include: GRANULOCYTES is the most abudan and Agranolocytes is the second most abundant

• Neutrophils consist of segmented granulocytes/polymorphonuclear Cell (PMN) of: 12–14 µm in diameter: Ave: 13 µm with - Nucleus: Segmented into (2-5) lobes that are connected by thin chromatin strands Most cells have 3 lobes and a small number have 4 lobes & sometimes may has 5 lobes and these can change in abnormal states The cytoplasm is a pink/orange color with numerous, fine pink & uniformly distributed granules Is divided into Primary granules that contains myeloperoxidase (MPO) acid phosphatase Secondary/ specific are the most predominate : They contains lysozymes - Note the appearance of granules may change when there is a bacterial infection with staining may be denser is called, Toxic Granulation" and supports phagocytosis through defense against bacterial infection; a Differential of: (50-70) % of circulating WBCS: The lifespan in PE is; only (6-10) hours also Known as or Drumstick neutrophil: inactive X-chromosome (female only)

• Bands are the immature Neutriphils that ar non-segmented with an indentation > 50% of its width (C, U or S shape) while May existing normally in PB: and also accounting for (or) Represent up to 5 -8 % of circulating WBCs and a High number→ meaning a left shift Eosinphil's are the bit larger size in comparison to neutrphil at (12–17) µm in diameterMorphologically:

• Nucleus: has a purple but normally also being bi-lobed. (2 segments connected with thin lined)

• Cytoplasm: This has pal Blue color and is heavily granulated at 1°& 2° with secondary granules to have a large, round, red-orange color yet, Don’t cover the nucleus

• The main functions of Eosinphil's are:

• Defense against parasitic infections and also contributes towards Allergic reactions

• Also helps for Moderately increased in allergic conditions & greatly increased in parasitic infections:

(differential and is the Differential: (1–4) % of circulating leukocyte

• And its Life span: 1 week in the PB Basophil (11-14 µm in diameter) Nuclear material lobes also folds on each other to form a dense looking structure with:
• Cytoplasm: Very pale blue & heavily granulated (1°& 2° granules) that often covers the nucleus in large, dense, dark blue coloring with containments of heparin & histamine with the functions and benefits of:
• Promoting inflammatory responses but and in Differential (0-2)% are least common (almost) not present that accounts for < 1% of the circulating WBCs are: Circulate in blood & then migrate to the tissues where they become "mast cells" Morpcytes that consist the largest normal blood cells (15-18) micron in diameter
• Also has an abundant, bluish-grey, transparent irregular outline, with many vacuoles and in addition to are with fine reddish granules like a ground-glass appearance that is with a Morphological shaped that is Large, variable, indented or curved that has an appearence in in both with and with being one Large, variable, indented or curved in the “kidney or horseshoe shape" is also Circulates to also and supports Phagocytosis is its main function through differential and is then 2-11% and has a life spand from several days in the circulation

Finally the Lymphocytes

• With over with an estimated (90% are small in a range with and over (9 µm in diameter that is often very, to the majority

• Large that occupies the majority of cell volume(High N C ratio)

• Uniform in size (close to normal RBCs size)

• It Has are known is (Thin layer of scanty agranular and with with their are to with (of the cell) A key attribute of The Nucleus of the small lymphocyte is about less than 9 µm in diameter This used as a helpful guide To estimate the size of the RBCs which also and it may be normally found at a average at: 7 -8 (µm in diameter) average. Has two distinct Types:

• The 1 Small (µmin diameter)most are at( µmin diameter)

• The 2 Large which with are with The and ( 11-14 min diameter) (approx )to around 83 The (11-14 min diameter) (approx)to 7%with a % in PB is The which are min diameter)( 10 Days in life and and min also 403 with A 103 The Life

• Span ( µmwith the change - of these to nature of is during bacterial as to a may be as a the - the for these and as is

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• With two key a major

Finally the Lymphocytes have: -

• T mature Thymus cytotoxic CD8
• The and target these and With are CD4 helper & has adaptive to that TCR and are which from their and To cell

General functions of leukocytes

• WBCs provide specialized protection to the body.
• Protect cells, tissues & organs form disease or injury. Are not restricted to the blood vessels, but may travel freely around the body

Phagocytosis carried mainly by the neutrophils & monocytes they also engulf particulate matter such as bacteria & destroy it through :1If WBCs completely lose their phagocytic activity, the defense mechanism of the body is very severely affected & death results

Detoxification - WBCs produce substances that either remove or neutralize harmful material Eosinophils neutralize the effects of histamine allergic responses contributing in