histo_mod2

PRECURSOR TO WHITE AND RED BLOOD CELLS

DIFFERENTIATE INTO UNIPOTENTIAL STEM CELL (CFU) AND THEN TO SPECIFIC BLOOD CELL LINES

SINGLE TYPE OF STEM CELL GIVES RISE TO ALL TYPES OF BLOOD CELLS IN BODY

DIFFERENTIATED PLEURIPOTENTIAL CELLS

CHANNELED INTO SPECIFIC CELL LINE

• MESOBLASTIC PHASE
• 3RD-9TH WEEK OF GESTATION - "BLOOD ISLANDS" DERIVED FROM MESODERM YOLK SAC
• PRIMITIVE BLOOD VESSLE FORMATION
• PRIMITIVE ERYTHROBLASTS

• HEPATIC PHASE
• 4TH WEEK TO BIRTH - MIGRATION OF PRIMITIVE ERYTHROBLASTS FROM YOLK SAC TO LIVER
• DEFINITIVE ERYTHROPOIESIS IN SPLEEN, LYMPH NODES AND THYMUS

• MYELOID PHASE
• 4TH-5TH MONTH OF GESTATION - MEDULLARY (MYELOID) HEMATOPOIESIS WITH EARLY SKELETAL DEVELOPMENT

AT BIRTH, MARROW IS ACTIVE IN HEMATOPOIESIS AND HEPATIC ACTIVITY IS MINIMAL

INFANT'S LUNGS REPLACE PLACENTA, 02 SATURATION INCREASES, AND ERYTHROPOIESIS PRODUCTION DECREASES (RBC's)

THROUGH EARLY PUBERTY, MARROW IN MOST OF SKELETON IS RED

BY EARLY ADULTHOOD ONLY VERTABRAE, RIBS, STERNUM, SKULL, PELVIS, AND PROXIMAL EPIPHYSEAL AREAS OF HUMERUS AND FEMUR HAVE RED MARROW. OTHER BONES FILLED WITH ADIPOSE YELLOW MARROW

YELLOW CAN CONVERT BACK TO RED IF DEMAND IS HIGH, EXTRAMEDULLARY (LIVER, SPLEEN, ETC) CAN KICK IN ALSO

FOUND BETWEEN TRABECULAE OF SPONGY BONE

• HIGHLY CELLULAR LOOSE CONNECTIVE TISSUE COMPOSED OF:
• HEMATOPOIETIC CORDS OF MATURING BLOOD CELLS ALONG WITH A SUPPORTIVE STROMA (esp RETICULAR CELLS AND MACROPHAGES)

VASCULAR COMPARTEMENTS - ONCE MATURED, BLOOD CELLS MOVE TO ADJACENT SINUSOIDS AND TRAVERSE ENDOTHELIAL LINING TO GET INTO CIRCULATIONAND VASCULAR COMPARTMENTS

GLYCOPROTEIN

STIMULATES STEM CELL DIFFERENTIATION - PROERYTHROBLASTS

PRODUCED IN KIDNEYS (MAYBE OTHER ORGANS)

PRODUCED IN RESPONSE TO CHANGES IN O2, BLOOD FLOW, HEME [ ], HEME/O2 SATURATION, etc

RENAL INSUFFICIENCY OFTEN ASSOCIATED WITH DECREASED ERYTHROPOIETIN LEADING TO ANEMIA

ELEVATED ERYTHROPOIETIN PRODUCTION SEEN WITH RENAL CELL CARCINOMAS, HEPATOCARCINOMAS, etc.

INCREASED ERYTHROPOIESIS CALLED POLYCYTHEMIA

RBC FORMATION 3-7 DAYS

ERYTHS MAKE UP 25-30% OF MARROW CELLS

ERYTHS OFTEN SURROUND MACROPHAGE CREATING ERYTHROBLASTIC ISLAND

DEVELOPING ERYTHROBLASTS THOUGHT TO RECEIVE IRON FROM THE MACROPHAGE AS THE FORMER DEVELOP

ERYTH

UNIPOTENT CELL DERIVED FROM PLURIPOTENT STEM CELL

NUCLEUS - REDDISH BLUE; CHROMATIN MORE DEFINED THAN MYELOBLAST

FREE RIBOSOMES AND NO CYTOPLASMIC GRANUALS

MITOTIC

GROWS INTO BASOPHILIC NORMOBLAST

ERYTH (FROM PRONORMOBLAST)

NUCLEUS - COARSENING OF CHROMATIN PATTERN (DARKER STAIN)

CYTOPLASM - INC AMOUNTS OF HEME BEGIN TO IMPART REDDISH TINGE

MITOTIC

GROWS INTO POLYCHROMATOPHILIC NORMOBLAST

ERYTH (FROM BASOPHILIC NORMOBLAST)

NUCLEUS - CHECKERBOARD PATTERN

CYTOPLASM - RED/BLUE

LAST ERYTH STAGE CAPABLE OF MITOSIS

GROWS INTO ORTHOCHROMATIC NORMOBLAST

ERYTH (FROM POLYCHROMATOPHILIC NORMOBLAST)

NUCLEUS - PYKNOTIC, OFTEN ECCENTRICALLY PLACED

CYTOPLASM - REDDISH PURPLE DUE TO HEME CONTENT

GROWS INTO RETICULOCYTE

ERYTH (FROM ORTHOCHROMATIC NORMOBLAST)

NUCLEUS - NO LONGER PRESENT

CYTOPLASM - REDDISH PURPLE DUE TO HEME, MAY CONTAIN GRANULOFILAMENTOUS MATERIAL (POLYSOMES, ER)

RESIDUAL RNA AND MITOCHONDRIA IN CYTOPLASM

RELEASED INTO GENERAL CIRCULATION, CONTINUES DEVELOPMENT INTO ERYTHROCYTE

FROM RETICULOCYTE

BICONCAVE DISCS

EOSINOPHILIC CYTOPLASM DUE TO ABUNDANCE OF HEME

LITTLE, IF ANY, RESIDUAL RNA OR MITOCHONDRIA

LIFESPAN 100-120 DAYS

GRANULOPOIESIS (TOTAL 2-3 WEEKS)

UNIPOTENT CELL (MYOBLASTIC) DERIVED FROM A PLURIPOTENT STEM CELL

NUCLEUS - ROUND, LIGHT REDDISH PURPLE, FINE CHROMATIN PATTERN

CYTOPLASM - BLUISH, NONGRANULAR

MITOTIC

RER

GROWS INTO PROMYELOCYTE

GRANULOPOIESIS (FROM MYELOBLAST)

NUCLEUS - BLUE, DEVELOPMENT OF DISTINCT (PRIMARY AZUROPHILIC) GRANULES

MITOTIC

GROWS INTO NEUTROPHILIC MYELOCYTE

GRANULOPOIESIS

NUCLEUS - ROUND, OVAL OR SLIGHTLY INDENTED ON ONE SIDE

CYTOPLASM - "DAWN OF NEUTROPHILIA" FIRST APPEARANCE OF NEUTROPHILIC (SECONDARY) GRANULES ADJACENT TO NUCLEUS

LAST MYELOBLASTIC STAGE CAPABLE OF MITOSIS

GROWS INTO NEUTROPHILIC METAMYELOCYTE

GRANULOPOIESIS (FROM NEUTROPHILIC MYELOCYTE)

NUCLEUS - INDENTED "KIDNEY BEAN SHAPE"

CYTOPLASM - NUMEROUS NEUTROPHILIC (SPECIFIC) GRANULES OUTNUMBER AZUROPHILIC NONSPECIFIC GRANULES

RARELY SEEN IN CIRCULATION OF NORMAL INDIVIDUALS, MAY BE SEEN IN MYELOCYTIC HYPERPLASIA

GROWS INTO NEUTROPHILIC BAND

GRANULOPOIESIS (FROM NEUTROPHILIC METAMYELOCYTE)

NUCLEUS - INDENTATION NOW HORSESHOE SHAPED, PYKNOTIC (VERY DENSE)

CYTOPLASM - NUMEROUS, EVENLY DISTRIBUTED NEUTROPHILIC GRANULES

GROWS INTO NEUTROPHIL

CAN BE FOUND IN NORMAL CIRCULATION

GRANULOPOIESIS (FROM NEUTROPHILIC BAND)

NUCLEUS - SEPARATED INTO DEFINITE 2-4 LOBES LINKED BY THIN STRANDS (SEGMENTED), HIGHLY CONDENSED CHROMATIN

CYTOPLASM - NUMEROUS EVENLY DISTRIBUTED NEUTROPHILIC GRANULES, AZUROPHILIC GRANULES ARE STILL PRESENT BUT NOT EASILY IDENTIFIABLE

• NEUTROPHILS 50-70%
• LYMPHOCYTES 20-40%
• MONOCYTES 2-8%
• EOSINOPHILS 1-4%
• BASOPHILS 0.5%

SERUM: PLASMA MINUS FIBRIN CLOT (FORMED BY COAGULANTS)

PLASMA: PROTEIN-RICH FLUID SURROUNDING THE BLOOD CELLS

PERCENTAGE OF WHOLE BLOOD SAMPLE OCCUPIED BY CELLS (Hct)

• MEN 47%
• WOMEN 42%

UNUSUALLY LARGE NUBER OF IMMATURE WBC's PRESENT

SUGGESTS UNUSUAL DEMAND FOR GRANULOCYTES (SIGNIFICANT INFECTION OR LEUKEMIAS

SHIFT TO THE RIGHT SUGGESTS INCREASED NUMBER OF AGED CELLS, AS WIT HPERNICIOUS ANEMIA (ie HYPERSEGMENTED NEUTROPHILS)

BONE MARROW CELLS THAT MAKE PLATELETS

DERIVED FROM MEGAKARYOBLASTS CONTAINING SINGLE LARGE NUCLEUS WITH MULTIPLE NUCLEOLI

POLYPLOIDY WITH LARGE IRREGULAR MULTILOBAR NUCLEUS (30x DNA AS DIPLOID CELL)

FOUND NEAR SINUSOIDS, CYTOPLASMIC PROCESSES EXTEND THROUGH SINUS WALL AND RELEASE PLATELETS INTO CIRCULATION