Connective Tissue (In General)
Form continuum with other three tissues,
Underlies epithelium, formes CT investement os skeletal muscle and peripheral nerves.
Special COnnective Tissue: blood bone, cartilage
Diverse functions: structural, muscle contraction harness, scaffolding, medium for metabolic exchange, aids in defense/protection, site of fat storage
ORIGIN: MESENCHYME: mesoderm and neural crest
VASCULARIZED: has blood vessels
Components
Cells and ECM -blood vessels -fibers -ground substance
ground substance
space between cells and fibers,
clear viscous with high H2O content
appears empty in Tissue Spread
-full of glycosaminoglycans(GAGs): repeating disacchride unit (sugars, carbs and NEGATIVE)
-proteoglycans: Core protein plus GAG’s (pipe cleaner), sulfated gags, HIGH negative charge, attract Na+ and H2O follows as hydration shell
become aggregates and bind to hyaluronan, link protein. even more H2O for gell like state as shock absorber
LM: stain with BASIC DYES (H&E-blue/purple)(PAS: Magenta)
-multiadhesive glycoprotiens: link to ECM & CT
Fibronectin, laminin, tenascin, osteopontin, entactin, nidogen
attach to integrins of cell
Fibers
Elastic Fibers
Collagen Fibers
Reticular Fibers
Elastic Fibers
like rubber band broken. (blunt end)
thinner than collagen, usually in branching pattern (collagen does not branch)
Function: permit tissue to be stretched or distended then return to original form
arranged as elastic sheets
interwoven with collagen fibers
PAS (magenta/dark) collagen light pale pink
H&E wavy hot pink lines (stain with eosin but not very well)
Orcein: Dark Brown or BLack
Gross level between vertebrae *ligament
Structure: elastin core and Fibrillin microfibrils
-very electron dense core
Clincal correlation: abnormal elastic fibers: joint hypermobility, rupture of lens and eye, dilation/dissection of the aorta, aneurism also chest deformity, long arm and long finger(arachnodidactyl), AKA PROBLEMS WHERE HIGH CONCENTRATION OF EF. aora, skin, ligaments
Collagen
highly conserved proteins
most abundant structural component
syntehsized by fibroblasts, epithelial cells, muscle and schwann
tensile strength
flexible but not elastic
28 types. we will know these
Fibrillar (I, II, III)
Sheet forming: (IV)
anchoring (VII)
Fibrillar Collagen
Type I II III
all mature to fibril stage, but not all form fibers of fiber bundles
- tropocollagen molecule (mature collagen)
- Fibril (orderly alignment of tropo molecules)
3 Fiber (bundles of fiber) - Fiber bundles
Fibrils
68nm periodicity
precise pattern of light and dark bands (TEM), orderly stacked assembly of molecules
identified by periodicity in lognitudinal sections
honeycomb of dots for cross section
bundles of striped lines from side
Type I Collagen
Most abundant and widely distributed
dermin, fascia, bone, ligaments, tendonds, sclera of eye, teeth (denin), organ capsul, scar tissue
TENSILE strength. STRONGEST
LM appearance:
H&E pink bundles with white arifact spaces
Trichrome: green or blue delicate fibers,
SEM: fibers and bundles
Type II Collagen
Cartilage, and vitreous of eye
hyalin cartilage, elastic cartilage, fibrocartilage,
function: restrains proteoglycan aggregan expansion, resistance to pressure
LM:
H&E Type II stains slightly acidophilic pink, however, at high concentrations of proteoglycans, they mask the stain to purple
more sporadic on TEM
Type III collagen
Fibrillar collagen that remains as fibrils
first tpe of collagen laid in embryo and in adult after injury, later replaced by type I
reticular fibers: heavily glycosylated Type III collagen fibers
LML seldom visible at H&E-sugars? What charge?
Silver: Stained BLACK
PAS: why not shown
in cell: reticular fibers: major structure of reticular lamina (BM)
surround adipocytes, smooth muscle fibers, periph nerver fibers, blood vssels
latticework around organs that
-filter blood, or lymph (spleen)
-rich microvasculature, liver endocrine
rapidly changing proliferating cells: bone marrow
Type IV Collagen
NO FIBRILS, NO PERIODICITY
monomers formflat sheets like mesh
ICC only for appearance
basal lamina, support and filtration
Type VII collagen
non fibrillar
anchoring fibrils
functions to anchor basil lamina to reticular lamina
Type I Collagen Defect
Multiple repeated bone fractures
brittle bone disease
eye portrusion:
What else??
Osteogenesis imperfecta
Type II Collagen Defect
Epiphyseal Growth plates
hyaline cartilage
how does that explain teh physical appearance? (short, curved back, large head)
Kniest dysplasia
Achondrogenesis type II
Type III collagen defect
Early morbidity from ruptured blood vessels and internal organs
joint hypermobility in digits
why early morbidity?
Aehlers-danlos
Type IV defect
Urinary problems, glomerulus BM problems, ultrafiltrate,
Hematuria, hearing loss
need think BL at filtration barrier
alports syndrome
type VII defect
what would be chief complaint?
severe blisters and scaring
Kindlers syndrome
