Hema - Hematopoiesis (Prelim).docx

**TYPES OF HUMAN STEM CELLS** \- first stage of cell **Totipotential Cells**\ -- cells are present in the first few hours after an ovum is fertilized\ - most versatile type of stem cell\ - can develop into any human cell type, including development from embryo into fetus **Pluripotential Stem Cel...

**TYPES OF HUMAN STEM CELLS** \- first stage of cell **Totipotential Cells**\ -- cells are present in the first few hours after an ovum is fertilized\ - most versatile type of stem cell\ - can develop into any human cell type, including development from embryo into fetus **Pluripotential Stem Cell\ **- cells are present in several days after fertilization\ - can develop into any cell type, except they cannot develop into a fetus **Multipotential Stem Cell**\ - derived from pluripotential cell\ - found in adults, but they are limited to specific types of cells to form tissues\ - Ex. Bone marrow stem cells can produce all types of blood cells, bone cartilage and adipose cells (fat) Site of Hematopoiesis by age **STAGES OF HEMATOPOIESIS** 1\. **Mesoblastic**\ - As early 19^th^ day gestation in the blood island of the yolk sac of the human embryo\ \> The blood islands will remain active for the 8 to 12 weeks\ \> Hematopoietic activity is confined to erythropoiesis\ \> Embryonic hemoglobin present:\ Gower 1, Gower 2, and Portland - Gower 1 (2 zeta, 2 epsolin) - Gower 2 (2 alpha, 2 epsilon) - Portland (2 zeta, 2 gamma) \- Embryo not fetus 2\. **Hepatic**\ - During the 3^rd^ month of gestation, from the yolk sac hematopoiesis now will be confined in the fetal liver (erythrocyte and granulocytes will be produced)\ - by the end of the 4^th^ month, primitive cell will start to disappear with an increase in the more definitive erythroblast, granulocytes and megakaryocytes\ - spleen, thymus, and lymph nodes will also be active in hematopoiesis\ - Hemoglobin present: Hemoglobin F, Hemoglobin A1, Hemoglobin A2 **3. Myeloid / Medullary (bone marrow)**\ - occurs between 5^th^ and 6^th^ month of gestation, the bone marrow becomes the primary site of hematopoiesis\ - at birth, the bone marrow becomes the primary source of cell production\ - Hematopoiesis occurs in most bones but primarily in the flat bones of the sternum, ribs, vertebrae, skull, clavicle, pelvis and long bones \> children, sternum, ribs, vertebrae, skull, clavicle, pelvis and long bones of the arms and legs\ \> while in adults, the principal source of production since it only occurs in the flat bones is the sternum **Bone Marrow Sites and Its Function** \- One of the body's largest organs\ - 3.5\ - consist of hematopoietic cells (erythroid, myeloid, lymphoid and megakaryocytes), fats tissue, osteoblast, osteoclasts and stroma Red marrow -- active (cell production),\ Yellow marrow -- inactive (fats or adipose)\ \ Retrogession -- red marrow become yellow\ Marrow cellular -- equal amount Bone marrow -- immature cells -- mature cell -- peripheral blood -- normal and functional blood **Cellular Elements of Bone Marrow** \- Pluripotential stem cell is the first in a sequence of step of hematopoietic cell generation and maturation.\ - The Progenitor of all blood cells is called multipotential hematopoietic stem cells **Hematopoietic cells 3 Phases according to Cell** **Maturity** 1. **Primitive, multipotential cells\ **- most immature group capable of self-renewal and differentiation into all blood cells 2\. **Intermediate cells**\ - group of committed progenitor cells (precursor cells) destined to develop into distinct cell lines 3\. **Mature cells (seen in peripheral blood)**\ - most develop group with specific function Granulocytes (BEN)\ - Basophil\ - Eosinophil\ - Neutrophil Earliest blast form of granulocytes\ - Myeloblast Protein\ - Hematopoietic growth factors -- stimulate or inhibit production of cells and precursor\ \> Cytokines CSF -- Colony Stimulating Factor\ CFU -- Colony Forming Unit **Examination of Maturing Cells** **General Cellular Characteristics**\ A. Overall Cell Size\ B. Nuclear -- Cytoplasmic ratio\ \> N:C (Nucleus and Cytoplasm) Nucleus -- contains DNA / genetic information\ Nuclei -- Chromatin Staining of cytoplasm\ - Deep Blue -- basophilic **Nuclear Characteristics** **Chromatin pattern**\ \> In general, the overall progresses from a loose-looking arrangement to a more clumped pattern as a cell matures. The terms used to describe various patterns include the ff:\ Smooth or homogenous, fine, delicate, lacy or thready, smudged, clumped, or pyknotic (dense compact) **Nuclear Shape\ **- shape of the nucleus in young cells is either round or oval, however monocytes may have slighty folded nuclear shape. In the cells that retain their nucleus as they mature, nuclear shapes become very distinctive for particular cell types\ Blast forms -- seen into nucleus\ RBC and platelets -- unnucleated but mature nucleated **Presence of Nucleoli\ **- presence and absence of nucleoli is important in the identification of cells.\ - 3 cell lines of erythrocytes, leukocytes and megakaryocytes all have nucleoli in the earliest cell stages.\ - As cell mature, nucleoli are usually not visible. These changes in the appearance of the nucleoli are related to the rate of synthesis of ribosomal RNA **Cytoplasmic Characteristics** 1\. Staining color and intensity -- cytoplasm immature (blue)\ 2. Granulation -- only WBC matures\ 3. Cytoplasmic shape\ 4. Quantity of cytoplasm\ 5. Vacuolization -- WBC with vacuoles -- monocytes\ 6. Inclusion bodies -- not normal to RBC and WBC