Lecture 5 - Blood and Bone Marrow Flashcards
Blood - what is it, what is equivalent to ground substance, solubility and what happens with clotting, how do you view blood cells and stains
-a specialized CT consisting of blood & immune system cells suspended in plasma
-plasma is tissue fluid equivalent to ground substance minus fibers
-fibres of blood are soluble; the proteins become fibrous upon activation of coagulation (clotting)
Blood cells viewed via cell smears
-special stain: (Wright’s) eosin + 2 different basic dyes
-basophilic substances still blue
even though hematoxylin not used
what are the three components of blood and what is included in each
- plasma - water(92%), proteins (7% by weight, albumin biggest part), other solutes
-erythrocytes
-buffy coat - platelets, leukocytes (neutrophils, lymphocytes, monocytes, basophils, eosinophils)
components of blood - formed elements and leukocytes - what are they, what are their features
“Formed Elements” = Erythrocytes & platelets (thrombocytes)
* no nuclei*
* “fragments” of cells
Leukocytes (white blood cells)
-Granulocytes:
* nucleated blood cells with specific granules or storage vesicles
-Agranulocytes:
* nucleated blood cells without “specific” granules
erythrocytes - what else are they called, what are they involved in, how abundant, staining, % hemoglobin, where is it present
- also called red blood “cells” (RBCs)
- involved in O 2 /CO 2 exchange and blood pH balance
- most abundant “formed element” in blood (~40% of volume)
- homogeneous eosinophilic cytoplasm – 30% hemoglobin
- present in most tissue sections; internal scale bar (7-8 μm)
erythrocyte morphology and staining
- anuclear bi-concave discs for maximum surface area
- very eosinophilic due to high hemoglobin (protein) content (NOT due to presence of
iron!)
leukocytes - what do they look like, what arent they involved in, what is their function, what are they associated with
- nucleated cells of blood are larger than erythrocytes
- not really involved in functionality of blood directly
- travelling from site to site & surveillance
- associated with responses to tissue damage, infection, immunity
blood and immune system cells - what do they come from, what does it give rise to, daughter cells, what happens when they go from bone marrow to the blood stream
- all blood and immune system cells come from a common stem cell precursor in the bone marrow
- common precursor gives rise to stem cells for erythrocytes and platelets, and for leukocytes
- these stem cells give rise to lineage specific progenitors
- daughter cells differentiate mostly in the bone marrow into the functionally different cell types
From the bone marrow, cells enter the blood stream and:
* stay in blood and act in blood
* travel via blood & exit into loose CT all over the body (transient CT cells)
* transient cells may re-enter circulation or remain in tissue
what cells are present in blood vs CT vs both
Blood - erythrocytes, platelets, monocytes, basophils
CT - marcophage, plasma cell (from B lymphocyte)
Both - lymphocytes, eosinophil, neutrophil
granulocytic leukocytes - what in included in this classifications, common features, unique features
-eosinophils, basophils, neutrophils
common features:
* derived from common bone marrow precursor
* multilobed nucleus
* auzurophilic granules (1o granules; lysosomes)
unique features:
* specific granules (2o granules)
* unique functionality for each cell type
Neutrophils (PMNs) - abundance, appearance and staining, function, how its seen in TEM
- most abundant granulocyte in blood
- multi-lobed nucleus; immature version has band-like nucleus
- pale, poorly stained cytoplasm
- specific granules not abundant or large, so best seen in TEM
- usually first immune cells to enter site of inflammation/infection; kill microorganisms by phagocytosis and secretion of antibacterial enzymes/peptides/ROS
eosinophils - size, appearance, what do they granules contain, function
- mid-sized & fairly abundant leukocyte in blood
- large bi-lobed (occasionally tri lobed) nucleus
- pale, poorly stained cytoplasm; large prominent eosinophilic specific granules
- granules contain rod-shaped inclusions visible in TEM
- kill endo-parasites (e.g. round worms, flukes, etc.) & modulate basophil and mast cell activity
basophils - how common, appearance, granule stain
- very rare; < 0.5% of all leukocytes
- large tri-lobed nucleus
- pale, poorly stained cytoplasm
- large deeply stained basophilic granules; may obscure nucleus
- granules stain metachromatic (cause color shift) with Toluidine Blue
basophil functions - where are cells release from and what is done, what does degranulation cause, mast cells
- cells released from bone marrow & circulate for short time
- modulate allergic reactions:
immediate reaction to second
stimulus by an antigen (via IgE) - degranulation causes vasodilation, edema, mucus
secretion, bronchiole constriction - can be life threatening: systemic
- Mast Cells are related cell type found in tissue- usually more localized response but can also
be systemic response
agranulocytic leukocytes - what cell types are included, how is it directly related to immune responses, general features
-lymphocytes, monocytes
-Directly related to immune responses:
- humoral immunity (lymphocytes)
- intrinsic immunity (monocyte/macrophage)
-General Features:
- no obvious specific granules
- azurophilic granules (lysosomes) as all leukocytes do; may or may not be obvious in LM
- nucleus not multilobed
- relatively sparse cytoplasm
lymphocytes - size, appearance, what is prominent and what does it look like
- smallest nucleated cell in blood; often not much larger than RBC
- very little cytoplasm; cytoplasm usually basophilic
- nucleus with dense heterochromatin; nucleus is often only prominent feature, especially in tissue sections
lymphocyte function - what is it involved in, type of lymphocytes and what they do, what is special about large ones, immunostaining, where do they transit between
- involved in targeted immunity: antigen specific, highly regulated and part of complex system
- 3 major types of lymphocytes:
B-lymphocytes (B-cells): Ig (antibody) production T-lymphocytes (thymus): recognition & regulation
NK cells (Natural Killer Cells): killing of abnormal cells - all 3 types look alike, but large ones can be activated cells or NK cells
- in general, need immunostaining to differentiate them based on surface molecules
- frequently transit between blood, CT and lymph
plasma cells - appearance, nucleus, cytoplasm staining, what are they differentiated from, what are they specialized for
- heterochromatic nucleus with obvious heterochromatin clumps
(‘clock face’ or ‘cartwheel’ chromatin) - nucleus eccentric; more extensive cytoplasm than lymphocyte
- cytoplasm basophilic with light-staining golgi zone
- differentiated daughters of B lymphocytes; only seen in CT and
lymphoid organs - clonally selected and specialized for secreting antibody
monocytes - size, appearance, granules
- largest blood cells
- indented, euchromatic nucleus, often kidney, ‘U’ or horseshoe
shaped (amount of nuclear indentation highly variable) - no specific granules but azurophilic granules (primary
granules) often prominent
macrophages - what do they differentiate from, what are they involved in, what happens to ones that exit in response to inflammation vs ones that are permanent, paraffin sections, TEM, best way to identify and what can you sometimes see in LM
- differentiate from monocytes after exit blood
- involved in inflammation, phagocytosis & immune responses (e.g. antigen presentation; cytokine production)
- additional specialized functions in some tissues
- ones that exit as a response to inflammation/tissue damage
look similar to monocytes, but with more phagocytic vesicles - ones that become permanent specialized residents look very
different and unique for each organ of residence
-Paraffin Sections - only dependable ID is through presence of phagosomes e.g.
uptake of particulate dyes or blood pigment
-TEM - abundance of lysosomes, phagocytic vesicles and residual
bodies - best way to identify macrophages is via presence of phagosomes
- in LM, sometimes can see engulfed pigments, etc., especially associated with hemorrhage
platelets - other name, size, appearance, functino, activated clotting cascade and what happens
- 2-3 μm diameter formed elements; derived from megakaryocytes
- no nuclei, but other organelles, especially granules that contain vasoactive substances, factors for clotting & clot dissolution, growth factors
- function in clot formation (hemostasis) & other signaling
- activated clotting cascade: conversion of plasma fibrinogen to insoluble strands of fibrin
- fibrin network traps RBCs and forms clot to prevent further blood loss
- other platelet factors trigger repair/healing
platelets and megakaryocytes - metakaryocytes apperance, where doe processes extend
- megakaryoctyes are large, multinucleated cells in bone marrow
- processes extend through blood vessels (sinuses) in bone marrow and platelets are fragmented off & released into blood
bone marrow - what is it the site of, where is it found, types of appearance
- site of production of blood cells; activity changes with age
- found in the medullary canals of long bone and in small cavities of cancellous bone
-two types based on appearance on gross examination: - Red marrow (active) = filled with blood and blood precursor cells
-Yellow marrow (inactive) = filled with adipocytes
red bone marrow - what does it contain (3), what is the function (3)
Contains:
* Reticular cells/fibroblasts (produce collagen type III) forming the connective tissue stroma called reticular tissue
* hematopoietic cords or islands containing stem cells and precursors of blood cells
* Sinusoidal capillaries, adipocytes and macrophages
Function:
* Hematopoiesis (formation of blood cells)
* Phagocytosis of old/defective
erythrocytes and recycling of
heme-bound iron
