Histology Connective Tissue

Front 1

Which germ layers does connective tissue come from?

Back 1

Neuroectoderm (neural crest)
Head mesoderm
Lateral mesoderm
Paraxial mesoderm

Front 2

Fibers and ground substance

Back 2

Extracellular Matrix (ECM)

Front 3

A tissue composed of 3 components: cells, fibers, and ground substance.

Back 3

Connective Tissue (CT)

Front 4

How does CT differ from epithelium?

Back 4

Contains an abundant of intercellular material or matrix.

Front 5

What are the functions of CT?

Back 5

Support
Defense
CO2 and O2 exchagne
Repair - wounds

Front 6

Describe the defensive function of CT.

Back 6

site of immune rxs, phagocytosis, physical barrier, limits spread of infection.

Front 7

Describe the supportive function of CT.

Back 7

Structure and packing

Front 8

What are the classifications of Embryonic CT?

Back 8

Mesenchyme
Mucous

Front 9

What are the classifications of Adult CT?

Back 9

Loose
Dense ---Irregular ---Regular
Reticular
Adipose
Specialized ---Cartilage ---Bone ---Blood

Front 10

Describe Mucous CT

Back 10

--ground substance predominates
--derived from mesoderm
--matrix containing stem cells
--long distance between cells
--present in umbilical cord and young tooth pulp

Front 11

What is another name for Mucous CT

Back 11

Wharton's jelly - gelatinous tissue in umbilical cord, a source of stem cells.

Front 12

Describe the cells found in Mucous CT.

Back 12

Matrix contains stem cells (pleuripotential).
--similar to fibroblasts or mesenchymal cells in morphology
--cells are ovoid or stellate shaped with thin cytoplasmic processes

Front 13

What cells come from Mesenchyme?

Back 13

Mesothelial
Endothelial
Osteoblasts
Chondroblasts
Adipocytes
Fibroblasts

Front 14

Describe Mesenchyme

Back 14

--Derived from mesoderm
--Mesenchymal cells (pleuripotent cells)
--Few fibers, some GS

Front 15

Describe function of Mesenchyme

Back 15

A transient CT which forms adult CT (including specialized)
ie muscle, endothelium, mesothelium, lymph nodes, spleen, blood cells, synovium, among others

Front 16

Describe mesenchymal cells

Back 16

Small and stellate with each cell capable of having many processes. These processes may form gap junctions with other cells.

Front 17

What are the two types of cells of CT proper.

Back 17

--Fixed (resident, permanent)-produce, maintain, serve as stores for fuel.
--Mobile (wandering, transient) - from blood, migrate due to reactions or "call".

Front 18

Fibroblast

Back 18

A former fibrocyte - inactive
Most abundant CT cell

Front 19

Describe structure of fibroblast

Back 19

--Stellate-shaped or spinde
--Ovoid, large pale staining nucleus
--basophilic cytoplasm - rER
--note rER and Golgi

Front 20

What is the function of fibroblast

Back 20

--(intense) synthesizing collagen, elastic and reticular fibers.
---------------ex. wound healing
--produce and maintain the ground substance.
--produces the extracellular fibers that serve a structural role in the tissue.

Front 21

Describe structure of fibrocyte

Back 21

--smaller than fb
--thinner spindle shape
--smaller, darker elongaed nucleus
--fewer organelles

Front 22

Describe the synthesis of materials by the fibroblast.

Back 22

--Procollagen is secreted and becomes both collagen ff. and reticular ff.
--Microfibrillar protein and proelastin form elastic ff.
--Proteoglycans are composed of hyaluronic acid and proteoglycan subunits.
--Structure glycoproteins, fibronectin, and laminin are produced.

Front 23

Describe function of fibrocyte.

Back 23

are inactive or maintain.

Front 24

List cell types associated with body's defense system that function within the ECM of the tissue.

Back 24

--lymphocytes
--plasma cells
--macrophages
--eosinophils

Front 25

Describe Myofibroblast

Back 25

--has stronger contractile properties
--adds alpha-smooth muscle actin regulated/Induced by TGF-B1
--differentiates from fibroblast and other cells.
--adds Mfs containing distinc actin - alpha-smooth muscle actin.

Front 26

Describe function of Myofibroblast

Back 26

usually acts as a single cell or in scattered groups in wound contraction and in some pathologies.

Front 27

Dupuytren's Disease

Back 27

Involves myofibroblasts of palmar fascia

Front 28

T or F
Myofibroblasts are found in the cornea.

Back 28

True

Front 29

What are some Histiocytes or CT macrophages and the locations their found.

Back 29

--LIver-Kupffer cells
--Lung-alveolar macrophages
--CNS-microglial cells
--lymph node, spleen
--epidermis-Langerhans cell

Front 30

Describe Histocyte

Back 30

--CT Macrophage
--Discovered by India ink uptake
--derived from blood cells called monocytes.
----bone marrow stem cells->monocytes->macrophages

Front 31

fibronexus

Back 31

--In a myofibroblast actin bundles transverse the cell cytoplasm originating and terminating on the opposite sites of the plasma membrane.
--The site of actin fibers attachment to the plasma membrane also serves as a cell to ECM anchoring junction and is called a fibronexus.

Front 32

T or F
Macrophages are phagocytotic cells derived from monocytes.

Back 32

True

Front 33

T or F
The macrophage contains a large Golgi apparatus, rER and sER, mitochondria, secretory vesicles, and lysosomes.

Back 33

True

Front 34

T or F
Mast cells develop in bone marrow and differentiate in connective tissue.

Back 34

True

Front 35

When macrophages encounter large foreing bodies, they may fuse to form a large cell with as many as 100 nuclei that engulfs the foreign body. These multinucleated cells are called?

Back 35

Foreign body giant cells (Langhans cells)

Front 36

Describe structure of Histiocyte or CT macrophage.

Back 36

--Large cells
--Cytoplasmic debris - secondary to lysosomes
-heterogeneous cytoplasm
-sometimes foamy
-irregular nucleus

Front 37

What are some contents of lysosomes?

Back 37

--Lysozyme
--hydrolases
--H2O2
--Collagenase
--GAGases,etc

Front 38

What is the function of CT macrophage or Histiocyte?

Back 38

--Ingestion & Digestion (Phagocytosis)
--Cell-mediated resistance to bact, virus, protozoa, fungi, tumors
--Destruction of rbcs
-Antigen presenters after processing = Antigen Presenting Cell (APC)

Front 39

Major Histocompatibility Complex II or MHC II

Back 39

Macrophages have specific proteins on their surfaces known as MHC II molecules that allow them to interact with helper CD4+ T lymphocytes.

Front 40

Antigen Presenting Cells (APCs)

Back 40

Macrophages engulf a foreign cell, antigens-short polypeptides from the foreign cell are displayed on the surface of MHC II molecules.
Macrophages present antigen to helper CD4+ T lymphocytes.

Front 41

What are some other products/factors related to macrophages?

Back 41

--Complement system
--coagulation factors
--interferon
--TNF----??????
--IL1--------???????
--Prostoglandins
--PAF

Front 42

Describe function of plasma cell?

Back 42

Synthesis of Abs or Igs

Front 43

Plasma cells are derived from what cell?

Back 43

B lymphocytes

Front 44

Where are Plasma cells most numerous?

Back 44

Loose connective tissue where antigens tend to enter the body (e.g., the gastrointestinal and respiratory tracts)
--normal component of salivary glands, lymph nodes, and hematopoietic tissue

Front 45

Describe structure of Plasma Cell

Back 45

--Ovoid shape but can vary
--spherical, eccentric(off set/not center) nucleus
--Juxtanuclear golgi
--Basophilic cytoplasm
--CLOCK FACE NUCLEUS

Front 46

T or F
Lymphocytes ( ie plasma cell) are most numerous in the lamina propria of the respiratory and gastrointestinal tracts, where they are involved in immunosurveillance against pathogens and foreign substnaces that enter the body by crossing the epithelial lining of these systems.

Back 46

True

Front 47

Describe structure of Mast Cell

Back 47

--Large Ovoid
--spherical nucleus
--homogenous cytoplasm
--Centrally-located oval nucleus
--cytoplasm filled with large, intensely basophillic granules.
--scroll or whorl patterns in granules

Front 48

T or F
Mast cells develop in the bone marrow and differentiate in CT.

Back 48

True

Front 49

Mast Cell

Back 49

--Mast-german for stuff
--Stuff=granules
--observed near bvs
--Lots of Fc receptors for IgE

Front 50

What is the function of the Mast Cell.

Back 50

--Store and release chemical mediators of inflammation & hypersensitivity
--Promotes allergic rxs known as anaphylaxis or immediate hypersensitivity rxs

Front 51

Describe granules of Mast Cells.

Back 51

--Contents of granules cause vasodilation/bronchioconstriction (working on smooth muscle)
--increase postcapillary venule permeability

Front 52

Cromolyn sodium

Back 52

cell membrane stabilizer

Front 53

What are the steps of Mast Cell Response

Back 53

1) 1-5 secs -- degranulation of primary mediators and lipid mediators of inflammation triggered
2) 5-30 mins -- PGE2 (prostoglandin) is a vasodilator; Leukotriene C4 (LTC4) induces vasoconstriction and also causes bronchoconstriction.
3) Hours -- TNF, interleukin, PAF stimulate protein synthesis

Front 54

Describe Histamine

Back 54

contracts visceral arterial (vasoconstriction) and bronchial smooth muscle (bronchoconstriction) and relaxes peripheral arterial smooth muscle (vasodilation) and contracts endothelial cells

Front 55

Describe Heparin

Back 55

is a sulfated GAG that is an anticoagulant. Its expression is limited essentially to the granules of mast cells and basophils.
--Unites with antithrombin III and platelet factor IV which can block numerous coagulation factors.

Front 56

Adipose cell

Back 56

--Fat cells
--Signet ring
--Fully-differentiated cells
--differentiate from mesenchymal stem cells
--gradually accumulate fat in their cytoplasm
--involved in the synthesis of a variety of hormones, inflammatory mediators and growth factors.
--capillaries come in contact with every adipose cell.

Front 57

T or F
The adipocyte is a connective tissue cell specialized to store neutral fat and produces a variety of hormones.

Back 57

True

Front 58

Describe structure of adipocyte

Back 58

--Contain one central droplet of fat in cytoplasm, formed from small droplets fusing
--Nucleus flattened
--typical mito, rER, sER around nucleus
--EACH CELL surrounded by a basal lamina (BL)
--Lipid is dissolved in preparation (appears as a white spot)

Front 59

Adipose tissue

Back 59

--accumulation of large numbers of adipocytes
--specialized

Front 60

Has potential to develop into endothelial cell, adipose cell, smooth muscle

Back 60

Pericyte

Front 61

Pericyte

Back 61

Adult Stem Cells or Undifferentiated Mesenchymal Stem Cell or Tissue Stem Cell

Front 62

Eosinophil

Back 62

--functions in allergic reactions and parasitic infections
--can be observed in normal CT, particularly lamina propria of the intestine, as a result of chronic immunologic responses that occur in these tissues.
--originates from hematopoietic stem cell

Front 63

Neutrophil

Back 63

--very limited affinity to stains.
--function in phagocytosis

Front 64

Lymphocyte

Back 64

--smallest of the wandering cells in the CT.
--they have a rim of cytoplasm surrounding a deeply staining, heterochromatic nucleus.
--often cytoplasm of CT lymphocytes may not be visible.
--small numbers throughout CT.
--Numbers increase dramatically at sites of inflammation caused by pathogenic agents.
--Most numerous in lamina propria of the respiratory and GI tracts.
--involved in immunosurveillance against pathogens and foreign substnaces.

Front 65

Produced by many cell types but predominately by fibroblasts, unique chemical composition.

Back 65

Collagen

Front 66

Describe organization scheme of collagen

Back 66

Collagen fibril -> collagen fibers ->collagen bundles

--cells (ex fibroblast) synthesize procollagen from amino acids
--It is then rapidly converted to collagen molecules
--In extracellular space they polymerize to form microfibrils (Mf) which make up a collagen fibril.
--Several fibrils form a fiber which form bundles.

Front 67

T or F
Collagen fibers are the most abundant type of CT fiber.

Back 67

True

Front 68

How does collagen appear in LM?

Back 68

--collagen fibers typically appear as wavy structures of variable width and indeterminate length.
--Stain readily with eosin and other acidic dyes.
--aniline blue use in Mallory's CT stain
--dye light green in Masson's stain

Front 69

How does collagen appear in TEM?

Back 69

--collagen fibers appear as bundles of fine, threadlike subunits called collagen fibrils.
--When stained wtih heavy metals, exhibit a sequence of closely spaced transverse bands. Banding pattern.

Front 70

Collagen Type I
Principal Tissue Distribution

Back 70

Loose and dense ordinary connective tissue; tendon, ligaments, fascia
Fibrocartilage
Bone
Dentin
Forms Fibrils

Front 71

Collagen Type I
Cells of Origin

Back 71

Fibroblasts and reticular cells; smooth muscle cells
Chondrocytes
Osteoblasts
Odontoblasts

Front 72

Collagen Type II
Principal Tissue Distribution

Back 72

Hyaline and elastic cartilage
Forms Fibrils

Front 73

Collagen Type II
Cells of Origin

Back 73

Chondrocytes

Front 74

Collagen Type III
Principal Tissue Distribution

Back 74

Loose connective tissue
fiber collagen
Papillary layer of dermis
Blood vessels
Forms Fibrils

Front 75

Collagen Type III
Cells of Origin

Back 75

Fibroblasts and reticular cells
Smooth muscle cells
endothelial cells

Front 76

Collagen Type IV
Principal Tissue Distribution

Back 76

Basil lamina
External lamina
Lens capsule of eye

Front 77

Collagen Type IV
Cells of Origin

Back 77

Epithelial and endothelial cells
Lens fibers

Front 78

Collagen Type V
Principal Tissue Distribution

Back 78

CT stroma

Front 79

Collagen Type V
Cells of Origin

Back 79

Fibroblasts, Reticular cells
Smooth muscle cells

Front 80

Collagen Type VII
Principal Tissue Distribution

Back 80

Anchoring fibrils
--securing BL to CT fibers

Front 81

Collagen Type VII
Cells of Origin

Back 81

Fibroblasts

Front 82

Collagen Type X
Principal Tissue Distribution

Back 82

Zone of hypertrophy

Front 83

Collagen Type X
Cells of Origin

Back 83

Chondrocytes

Front 84

Describe Reticular Fibers

Back 84

--Produced by fibroblasts, reticular cells, and others
--Composed of type III Collagen
--exhibit branching, typically do not bundle to form thick fibers.
--

Front 85

T or F
Reticular fibers provide a supporting framework for the cellular constituents of various tissues and organs.

Back 85

True

Front 86

How do Reticular Fibers stain

Back 86

--in routinely H&E preparations, reticular fibers cannot be identified positively.
--threadlike appearance
--readily displayed by means of PAS stain.
--argyrophilic - appear black with special silver staining
--mesh like pattern or network (anastomosing)

Front 87

Reticular fibers
common sites

Back 87

--In loose CT, networks are found at the boundary of CT and epithelium as well as surrounding adipocytes, small blood vessels, nerves and muscle cells.
--embryonic tissue
--prevalence indicator of tissue maturity
--prominent in initial stages of wound healing
--not in thymus