HistoReview_2ndShift.pdf

UST FACULTY OF MEDICINE AND SURGERY Class of 2016 o

Histology Second Shifting Reviewer

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BLOOD  

Consist of a variety of cells suspended in plasma Plasma is composed of: o 90% water o 8% protein  Includes blood coagulation proteins, albumin, globulin  Nearly all derived from synthesis in the liver except for immunoglobulins from plasma cells  Exert colloidal osmotic pressure within the circulation o 1% inorganic salts o 0.5% lipids o 0.1% sugar

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Histological Methods  

Romanowsky-type Staining Technique: gemsa, wright, leishman Staining characteristics: o Basophilia: affinity for basc dye methylene blue; for DNA nuclei and RNA in the cytoplasm o Azurophilia: affinity for purple azure dyes; for lysosomes o Eosinophilia: affinity for acidic dye eosin; for haemoglobin o Neutrophila: affinity for salmon pink/lilac dye (not necessarily with neutral pH); for neutrophil granules

Erythrocytes    

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Function in O2 and CO2 transport Lifespan: 120 days Fully differentiated form: outer plasma membrane enclosing haemoglobin and some enzymes Staining: o Stains pink due to haemoglobin, a basic protein o Pale staining at the center is attributable to its biconcave shape Biconcave disc shape o 7.2 micrometers in diameter o Provides 20-30% more surface area, enhancing gas exchange o Allows deformability, thus RBCs can pass through small capillaries (3-4 micrometers in diameter)

Determined by cytoskeleton and water content o Main determinant of lifespan Plasma Membrane o Lipid bi-layer o Blood group substances on the surface o Spectrin: main skeletal protein Metabolism o Energy derived from anaerobic metabolism of glucose because of the absence of mitochondria o Energy needed to maintain electrolyte gradients o Energy also needed to maintain iron in divalent form and sulfhydryl groups in reduced, active form Reticulocytes o Immature RBCs that still retain residual nuclear material o Released into the circulation from the bone marrow o Final maturation into erythrocytes occur 24-48 hours after release o Supravital staining is used for detection which forms a blue-stained reticular precipitate o Reticulocyte percentage is a useful indicator of erythropoiesis; high levels are present when there is increased RBC production

Granulocytes    

With prominent cytoplasmic granules All have single multi-lobed nucleus, and thus assumes many morphological shapes Also called polymorphonuclear leukocytes, with neutrophils as the ones exhibiting the greatest polymorphism Myeloid cells, with exclusive origin in the bone marrow

Neutrophils  40-75% of circulating leukocytes  Principal function for the inflammatory response; degenerates after engulfing bacteria and do not re-enter the circulation  Highly motile through pseudopodia and exhibit crawling movement  Highly lobulated: usually 5 lobes  Highly condense chromatin indicating latency  Anaerobic mode of metabolism  Neutrophilia: increased neutrophil count in acute inflammation, bacterial infection  Drumstick Chromosome D o Small drumstick appendage in the neutrophils of females

By: Sachi Estreller |Section B

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UST FACULTY OF MEDICINE AND SURGERY Class of 2016

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o Condensed, quiescent X chromosome o Also called the Barr Body Granules o Primary Azurophilic Granules  Stain purple, spherical  First to appear during differentiation  Contain microbicidal myeloperoxidase and neutrophil defensins  Contribute to killing and degradation of MOs o Secondary Granules  Most numerous, rod-like  Contain laysozyme, gelatinase, collagenase, lactoferrin, cathelicidins, transcobalamin-1 o Gelatinase/ Tertiary Granules  Secrete enzymes for tissue degradation  Contain gelatinase which breaks down ECM and insert adhesion molecules into cell membrane o Secretory Granules  Reservoir for membraneassociated receptors needed for neutrophil function  Also contain alkaline phosphatase and albumin Neutrophil Functon o Chemotaxins  Attract neutrophils when released by damaged tssue or during antibody response  Stimulate fusion of secretory granules to cell surface o Opsonization  Coating of organisms with antibodies  Enhances phagocytic activity o Phagosome Formation  First step in phagocytosis  Organism surrounded by pseudopodia which then fuse and form a phagosome  Phagosome fuses with primary granules o Degranulation  Secretion of granule contents into extracellular environment  Occurs first in secondary  gelatinase  specific granules

Eosinophils  1-6% of circulating leukocytes  With bilobed nucleus, often obscured by cytoplasmic granules  Exhibit diurnal variation, being greatest in the morning and least in the afternoon  Circulate for 8-12h then emigrate from capillaries to tissues  Chemotaxis o Release of eotaxin, IL-5 and eosinophil chemotactic factor of anaphylaxis o Responsible for recruitment of eosinophils to tissues, especially the spleen, lymph nodes, and GI tract  Granules o With large ovoid eosinophilic specific granules, containing an elongated crystalloid o Crystalloid consists of major basic protein, hydrolytic lysosomal enzymes, and eosinophil peroxidise o Smaller granules contain aryl sulphatase and acid phosphatase  Eosinophil Function o Central role in induction and maintenance of nflammatory responses due to allergy o Also important in defense against parasites o Modulate local immune responses by producing tumor necrosis factor, transforming growth factor, GM-CSF, and IL-4,5,8 o All have receptors forIgE; IgG and complement receptors are also present o Minor role as antigen-presenting cells Basophils  Least common leukocyte,