20110119 05 connective tissue notes

From Iusmhistology

• started here on 01/19/2011 at 2PM.

Contents 1 Connective Tissue 1.1 Medical case 1.2 Birth of rock n' roll 1.3 Age of the Bobby's or Elvis lite 1.4 Beatles 1.5 The aging of Keith Richards 1.6 Summer of love 1.7 Punk rock: the second British invasion 1.8 Late 70s, early 80s 1.9 Twin study 1.10 BritPop: The third british invasion 1.11 Late 90s 1.12 Changes in connective tissue 1.13 Section of skin 1.14 Components of connective tissue 1.15 Compnents of connective tissue 1.16 Ground substance 1.16.1 Another componetn of ground substance 1.16.2 Integrins 1.17 Collagen 1.17.1 Fibrillar collagens 1.17.2 Type 4 collagen 1.18 Collagen synthesis 1.19 Reticular fibers 1.20 Elastic fibers 1.20.1 State 1 1.20.2 Stage 2 1.20.3 Stage 3 1.21 Sun exposure comparison 1.22 Cells 1.23 =Mesenchymal cells 1.23.1 Fbs 1.23.2 Adipocytes 1.23.3 Macrophages 1.23.4 Would healing 1.23.5 Mast cells 1.23.6 Plasma cells 1.24 Loose connective tissue versus dense 2 Lab 5: Connective Tissue 2.1 Objectives: 2.2 CONNECTIVE TISSUE FIBERS 2.2.1 Collagen fibers 2.2.1.1 Loose connective tissue 2.2.1.2 Dense irregular C.T. 2.2.1.3 Dense regular C. T. 2.2.2 Elastic fibers 2.2.3 Reticular fibers 2.2.3.1 Reticular connective tissue 2.2.3.2 Embryonic connective tissue (Mesenchyme) 2.3 THE CELLS OF CONNECTIVE TISSUE 2.3.1 Fibroblasts 2.3.2 Plasma cells 2.3.3 Lymphocytes 2.3.4 Macrophages 2.3.5 Adipose Cells 2.3.6 Mast Cells

[edit] Connective Tissue

• Imagine the oldest person you know...naked. That's connective tissue deficiency.

[edit] Medical case

• Keith Richards
  • Guitarist, rock musician.
• Sex and drugs and rock n' roll is embodied by Mr. Richards.

[edit] Birth of rock n' roll

• About 1940's.
• First rock stars were black.
• The girls loved these rock stars.
  • And the boys tried to be like the rock stars.

[edit] Age of the Bobby's or Elvis lite

• Bobby Vee, Bobby Darin, Bobby Rudell, etc.

[edit] Beatles

• Beatles hit.
• Then things diversified a bit.
• We'll focus on British rock.

[edit] The aging of Keith Richards

• Three layers to the skin:
  • epidermis (keratinized),
  • dermis (collagen, elastic fibers, several cell types).
    • Nourishes epidermis
    • Forms barrier to the rest of the body.
    • Involved in ion and water transport
  • Subcutaneous fat
    • Helps sculpt face.
    • Stores TAGs
    • An endocrine organ, too.
• All three give shape and structure to skin.

[edit] Summer of love

• Lots of drug use: lsd, cocaine, etc.

[edit] Punk rock: the second British invasion

• Sex pistols, elvis costello, etc.
• Less about music, more about chaos and noise.
  • About lifestyle.
• Alcholol abuse
  • Edema occurs because connective tissue cannot control water and ion passage

[edit] Late 70s, early 80s

• Richards: kept late hours, smoked, drank

[edit] Twin study

• Shows that twin that smokes have more wrinkles and lines in the face.
• This is called elastosis
  • Collagena ndn elastic fibers are losing their strength.
• Shows that twin in southern climate has more sun damage
  • Lines, wrinkles, folds.
  • Due to damage of connective tissue proper layer.
• Shows that twin with excess weight can hide the lines and wrinkles and such.

[edit] BritPop: The third british invasion

• Punk rock is mainstreem.
  • Radiohead
• Richard has deep lines, lossing elasticity in the neck.
  • Looks like a turtle neck.
• Ground substance = glycoaminoglycans, among other fibers.
• Recent data says that wrinkles are caused by a change in cell population and composition of ground substance.

[edit] Late 90s

• Losing bone mineral density.
  • Bone is a specialized connective tissue.
  • Smoking and drinking will cause bone to be lost.
• Immune system is compromised.
• Swollen joints
  • Cartilage and bone and synovial fluid all become inflamed.
  • This is enhanced by drugs, sex, and rock and role.
• Excessive bruising is also a result of damaged connective tissue.

[edit] Changes in connective tissue

• Skin
  • Wrinkling, less elastic.
• Fat gets redistributed
  • This is important in storage of TAGs.
• Bone and cartilage:
  • Decreased bone density
  • Attenuated join mobility
• Blood
  • Decreased immune system

[edit] Section of skin

• Pink ribbons are collage fibers.
  • Note these are fibers not fibrils which can only be seen in EM.
• Ground substance is a viscous fluid that helps hold everything together.
• Fibroblasts make fibers and ground substance.
• Macrophages are patrolling.
• Mast cells are around capillaries.

[edit] Components of connective tissue

• Study on your own.
• Separates proper connective tissue (today's topic) from the specialized types (bone, blood).

[edit] Compnents of connective tissue

• Visual organization of the types of connective tissue.

[edit] Ground substance

• Clear, viscous fluid, in between fibers.
• All components work together to act as an integrated hold.
• Made up of glycosaminoglycans and ...
• Glycosamino glycans:
  • Put into aggregates via hylauronic acid.
• Glycosaminoglycans (GAGs)
  • Long, linear polydisaccharides
  • Consist of two different sugars
  • Have lots of sulfur
    • Except one:
  • Know where these are found
  • Typically linked to a core protein.
    • There are multiple flavors.
    • Syndecan (integral membrane protein)
    • Versican (
    • Aggrecan
  • This aggregation makes them look like a bottle-brush.
  • Typically about 800 units in length.
  • Amino terminus:
    • Has a hyluronic binding region; binds HA via linker protein.
  • Over too units can bind to core protein.

• • Proteoglycans "along with their GAGs" can be further associated with...
    • This makes them huge.
    • These are negative so they attrach positive ions and polar water like a sponge.
    • this makes the aqueous fluid very viscous.
    • This allows your joints to be cushioned.

[edit] Another componetn of ground substance

• Laminin (not lamin)
  • 3 peptides
  • form a cross
  • Binding sites for just about everything in the BM
    • Type IV collagen
    • Heparin sulfate
    • Integrins
    • Collagens, sulfates, lipids, etc.
  • Molecular velcro
• Fibronectin
  • Again, a velcro
  • many binding sites

[edit] Integrins

• Dimeric proteins with alpha an dbeta subunit.
• Connect via talon on the inside of the membrane
• Signaling goes inward and outward.
• This is how the cell knows where it is and who its neighbors are and what it should be doing.

[edit] Collagen

• 30% of our body by dry weight.
• 21 genes
• Presence of collagens was critical to metazoans
  • Ability to put body parts together.
• Gly-X-Y repeats are really impt.
  • Forms a left handed helix.
  • However, collagen is always found in triple helix turn that has a right handed turn.
• Type 1
  • Two 11 chains and 1 12 ...?
• We need to know four of the 21 collagens: 1, 2, 3

[edit] Fibrillar collagens

• We need to knwo collagen 1, 2, and 3
• 1, 2, and 3 for fibrils
  • only visible in em
• 1 and 3 also form collagen fibers
• Fibrils spontaneously line up in head to tail conformation
  • Upon staining, fibrils will give distinct 67 nm periodicity.
  • In an EM, this is a big hint that you're looking at some type of collagen.

[edit] Type 4 collagen

• Type 2 will be mentioned more in cartilage talks.
• Has gly-x-y repeats
• Has helical regions
  • Interupted by non-helical regions
• Interuptions allow for flexible kinks.
• Head molecule allows for interaction with other collagen fibers.
  • This allows for a network of type IV to be made.
  • Thisis the foundation of the BM.

Get the name of the head.

• Perlecans help hold the mesh together.
• In mr. richard's wrinkeles, type 4 is dissappearing.

[edit] Collagen synthesis

• Just like any secretory protein.
  • STarts on rER.
  • Has signal peptide, called preprocollagen.
  • Lysines are hydroxylated
    • Requires vit c; survvy
  • Glycosylation in ER
    • Different types get different amounts of glyco...
  • Signal peptide cliped
  • Registration peptids allow proteins to line up to become triple helix
  • Sent to golgi
  • Sent to just inside the membrane

• • Secreted
  • Collagen lines up

Look at this in the book.

[edit] Reticular fibers

• thin, hard to see in H&E
• 0.5 to 1 micron
• that's for type 3
• Type 1 reticular fiber is larger and easier.
• We stain with silver to turn sugars black.
• Found most readily in hematopoietic areas: spleen, lymph nodes, bm

[edit] Elastic fibers

• Collagen mediate tensile strength.
• Elastic fibers give stretch.
• Three stages in fiber synthesis

[edit] State 1

• Oxytalan fibers
• Made of ...
• Form scaffold for ?
• Resist stretch
• When oxytalon fibers are lost, skin just hangs.

[edit] Stage 2

• Elaunin
• At this stage, deposits of elastin are irregularlly place thorught he scaffold of oxytalan.
• Elastin is a globular protein with glycine and proline in it.
  • Looks like natural rubber
• Elastin is secreted around these fibers.

[edit] Stage 3

• As secretion (by fb) continues, the elastin fibers crosslink (giving stretchability) and organizes in a regular way between fibrils.
• This gives skin the smooth and supple look.

[edit] Sun exposure comparison

• Black is ground substance.
• Changes at wrinkle
  • Oxytalons are gone (usually rists stretching)
  • Type 4 collagen atrophies
  • Condroitin sulfate is starting to disappear (ground substance is disaapearting)
  • Elastosis
    • Collagen and elastin fibers are tangling and nonfunctional
    • Elastins are thickening and not stretching
    • Collagen is hardening and not bouncy.
• Fb differences:
  • The superficial fbs are important in nourishing the tissue.
  • In wrinkles, the superficial fbs are gone and replaced by deeper ones that aren't as good at providing for the tissue.

[edit] Cells

• We need to knwo the two stem cell pops from which connect tissue comes
  • Fibroblasts: make ground and connective tissue
    • Most important
  • Adipocytes
  • Osteoblasts

• HSCs
  • Plasma cells and b lymphocytes and monocytes and macrophages and mast cells all come from this.

[edit] =Mesenchymal cells

• Look for pale staining areas that don't look like anything.
  • This is where you'll find non-committed mesenchymal stem cells.
• Pale nuc, clear.

[edit] Fbs

• Making ground subs, collagen, etc.
  • So they are close to these things.
• Oblong nuc
• Euchromatic nuc when active

[edit] Adipocytes

• Look like chicken wire.
• Stians black with osmium.
• Look for some brown fat.
  • It will have multiple lipid droplets.
• White fat is true storage of TAGs; brown fat is for heat generation.

[edit] Macrophages

Spaced out.

• These are different for each type of tissue.
  • For now, know that they look for invaders in connective tissue.
• usually bigger than most cells around them.

[edit] Would healing

• three steps:
  • inflammation
    • Macrophages kill invaders, release cytokines, bring in wound-repair machinery
    • FB important for cell proliferaiton

• step 2?
  • Main player?
  • Remodeling
    • FB are the main soldiers in remodeling.

[edit] Mast cells

• In connective tissue
• In dermis and capillaries
• In breast sections
• Often have metachromatic (blue toluene makes them reddish-purplish) color
• Seretory granules have mediators to hypersensitivity:
  • histamines, condroitin sulfate (parasites), etc.
• Immediate hypersensitivity: read the small sectionin the book.
• OfGten scattered around the cell.
• Granules seen by focusing upand down.

[edit] Plasma cells

• Lymphocytes that make Ab
• Found near glandular tissue
• Eccetnrically located nuc (like mast cells)
  • Clockface (what?), looks like polka-dots to me.
• Pale staining golgi
• Lymphocytes are almost all nuc and very heterochromatic

[edit] Loose connective tissue versus dense

• Loose connetive:
  • Fibers in all directions
  • Quite cellular: mcf, fb
  • Lots of ground substance (or where it was)
  • Near epithelial layers
  • Orcein stain will show elastin fibers
    • Elastin can be made in sheets in that form the lamina in smooth muscle of arteries.
• Dense irregular
  • Not as many cells
  • Less ground substance (or white space)
  • No specific orientation
  • Lower part of dermis
• Dense regular tissue
  • Tendons and ligaments
  • All fibers in one direction
  • Very little ground substance
  • All nuclei lined up in the same direction.
    • They are very elongated.

[edit] Lab 5: Connective Tissue

[edit] Objectives:

1. Compare the characteristics, and relative abundance of fibers, cells, and ground substance in each of the connective tissues.
2. Be able to identify the various connective tissue types.

[edit] CONNECTIVE TISSUE FIBERS

[edit] Collagen fibers

• Collagen stains pink upon H&E staining.

[edit] Loose connective tissue

• Examples of loose connective tissue include jejunum, just deep to the mucosal tissue and in the trachea, just deep to the epithelial layers.
• Slide 48 trachea
  • H&E
  • Connective tissue is subjacent to the epithelium.
  • Pink ribbons are aparent.
  • Nuclei identify the fibroblasts within the ribbons.
• Slide 95 jejunum
  • H&E
  • Connective tissue of the submucosa
• Slide 97 jejunum
  • Masson's trichrome stain
  • Collagen stains blue

[edit] Dense irregular C.T.

• Slide 31 palmar skin
  • Note the reticular dermis (see Basic Histology 18-1, Wheater 9.12) which shows the nice wavy ribbons of collagen as opposed to swirls and irregularity.
  • The papillary layer was thinner than I expected.
  • The difference between papillary and reticular layers was much less than I expected.
  • One difference was that reticular seemed to have thicker fibers, even if they weren't that much less squiggly.

[edit] Dense regular C. T.

• Slide 1 tendon
• Note that the tissue is very homogenous because all the fibers lie in paralle.

[edit] Elastic fibers

• Elastic fibers are difficult to find because they are found in such small quantities and do not stain well.
  • Look for them in large arteries or prominent elastic lamina where they are most concentrated.
  • Use orcein to stain elastic fibers brown or black.
• Slide 10: Mesentery
  • Here elastic fibers can be seen as black on the double stained orcein and H&E.
  • The elastic fibers are present in both the vessel wall and in the loose connective tissue.
    • Elastic fibers in the walls of the arteries form thick layers called "lamanae".
  • Note that the elastic fibers are much thinner and more defined that the wide, wispy collagen fibers.

• Slides 48 (Trachea) and 31 (skin) have elastic fibers but without orcein, they are difficult to see.

[edit] Reticular fibers

• These fibers stain black by silver impregnation techniques (i.e. are argyrophilic).

[edit] Reticular connective tissue

• Slide 22: lymph node
  • Uses a Wilder's reticular stain
  • Reticular fibers are small enough that they are best seen on the highest power.
    • Reticular fibers are black
    • Collagen fibers are brown
• Most reticular connective tissue is made up of reticular fibers.
• Reticular connective tissue is found both in and around the node.

[edit] Embryonic connective tissue (Mesenchyme)

• Mesenchyme is located between developing skin, muscle, and bone.
• The major component is reticular fibers which are difficult to see in many sections.
  • Look for areas where the cells can be seen as distinct, individual cells.
  • Turn the light down, too.
• Mesenchyme will look like mostly empty space with widely distributed cells sending off thing tendrils.

• Slide 4: Fetal limb:

• Slide 39: Fetal jaw:

[edit] THE CELLS OF CONNECTIVE TISSUE

[edit] Fibroblasts

• Slide 31: skin
  • Look for the dense connective tissue below the stratifed squamous keratinized epithelium.
  • Fibroblasts can be seen as elongated, deep-purple stained cells.
• Note that nuclei with less staining have more euchromatin and therefore are more active than those with darker staining.
• Furthermore, active cells will be larger.

[edit] Plasma cells

• Plasma cell characteristics:
  • eccentric nucleus,
  • clock-face nucleus (chromatin clumped toward the periphery, like numbers on a clock),
  • pale staining golgi region, (next to the nucleus)
  • basophilic cytoplasm that stains smooth and not grainy
• Other cells that are found in the connective tissue include:
  • Macrophages (won't have clock-face nuc, will have extensions of cytoplasm)
  • Mast cells (will have granules)
  • Basophils (will have ganules)
• Other clumped nuclei-containing cells are lymphocytes but B and T cells cannot be differentiated in H&E, usually.

• Slide 43: uvula

[edit] Lymphocytes

• Lymphocytes are found in loose connective tissue of the gut and respiratory tract and in lymphoid organs like the spleen, gut, and lymph nodes.
• Most lymphocytes are dominated by the nucleus, and may have just a thin rim of cytoplasm.

• Slide 24 lymph node
  • The densely packed areas of cells are called lymphoid nodules

• Slide 43: Uvula
  • A good place to find fibroblasts and lymphocytes.

[edit] Macrophages

• This stain is achieved by letting the macrophages injest carbon particles, making the macrophages black.

• Slide 36 leopard lymph node

[edit] Adipose Cells

• Adipose cells can occur singly or in clusters.
• Fat cells are seen as vacancy with a thin rim of cytoplasm when sections are prepared via formalin fixation (with dehydration with alcohol and xylene).

• Slide 78 mammary gland:
  • Note that the ducts are lined with simple, two-layer cuboidal epithelium.
  • This mammary tissue contains loose irregular and dense irregular connective tissue as well as adipose tissue.

• Slides 30, 31 skin:

• Slide 9 sciatic nerve (osmium fixed):
  • Fixed with osmium tetroxide to preserve the lipid as black.

[edit] Mast Cells

• Mast cells have cytoplasmic granules.
  • These usually do not show up in H&E sections.
  • Often the cells appear to be broken, to have spilled their granules.
• See Wheater 4.18; Gartner plates 3-3, 3-5, 3-6; Basic Histology 5-5.

• Slide 78:
  • look for cells with a
    • round nucleus,
    • cytoplasm that is filled with small reddish granules.

• stopped here on 01/19/2011 at 3PM.