Lecture 8 Flashcards
where does connective tissue originate from
embryonic mesoderm
what is connective tissue composed of
cells and ECM
function of connective tissue
1) structural support
2) medium of exchange
3) defense and protection
4) storage of fat
what is the ECM composed of
ground substance, fibers, structural glycoproteins
what is ground sybstance
GAGs and proteoglycans (proteins and GAGs together)
GAG types
1) hyaluronic acid (NOT sulfated or bound to a protein, bind to proteoglycans covalently)
2) chondroitin sulfate
3) dermatan sulfate
4) keratan sulfate
* all sulfates bind to water
fiber types in connective tissue
collagen fibers, reticular fibers, elastic fibers
major collagen types
I, II, III, IV
type I collagen
tendon, ligaments, bone, fibrous cartilage, dermis of skin
type III collagen
reticular. Lymphoid organs, muscle cells, blood vessels, liver, and endocrine glands
type IV collagen
basement membrane of epithelium, endothelium, muscle, and nerve axons. DO NOT FORM FIBRILS – mesh like!
in H&E collagen stains
acidophilic
what does mallory trichrome stain
type I and III collagen stained blue
type I, II, and III collagen properties
mechanical support, give tensile strength to tissue, resistance to stretching when pulled
type I collagen fibrils
tropocollagen, hydroxyproline STAIN IN BANDS
EM of fibroblasts
have RER and golgi for synthesis of procollagen
chain of procollagen to fibrils
procollagen –> ECM—>tropocollagen–>polymerization into fibrils
what stains type III collagen only
silver stain
which is thicker between type I and III collagen
type I – reticular fibers thinner. Reticular fibers are 6-12% hexose sugar residue vs 1% in type I
basement membrane made of
laminin, entactin, type IV collagen, GAG (heparan sulfate)
elastin made of
desmosine and isodesmosine
microfibrils made of
fibrilin
elastic fiber in H&E stain
fibers thin and branched, forming irregular networks
properties of elastic fibers
stretchable as rubber, up to 150%
elastic fibers produced by
fibroblasts (esp in CT), smooth muscle cells (esp of arteries), chondroblasts and chondrocytes in elastic cartilage
types of connective tissue proper
loose ct and dense ct (dense irregular and dense regular)
specialized CT
reticular, elastic, adipose
embryonic ct
mesenchyme, mucous
loose ct characterizations
more cells than fibers – most tissue and organs!!
lamina propria
mucous membranes – mostly type III collagen
dense irregular ct
more collagen fibers than cells - largely type I and III, some elastic. think dermis!
dense regular
parallel bundles of collagen fibers sep. by linear rows of fibroblasts. Type I - tendon, ligament
reticular tissue
type III, supportive stroma of tissue and organs (esp lymphoids – lymph node and spleen)
elastic tissue
in walls of arteries and epiglottis (resorcin fuchsin)
adipose tissue stain
one large single fat droplet - H&E look empty with white
adipose tissue function
in subcutaneous tissue, omentum, mesenteries, breast, bone marrow. insulator, storage of energy as triglycerides and release free fatty acids
shape of mesenchymal cells
stellate or spindle, delicate branching of cytoplasmic process surrounded by ground substance – unspecialized and can differentiate into almost all cell types in connective tissue
embryonic connective tissue
umbilical cord - mucous connective tissue WHARTONS JELLY
stroma
connective tissue in an organ
parenchyma
cells supported by stroma
fibroblast
spindle shaped with elongated nucleus, slightly basophilic cytoplasm due to RER , production of ECM
mast cells
single nucleus, strongly acidophilic cytoplasm, finely granular
mast cell granules contain
heparin and histamine
what receptors do mast cells have on their surface
IgE
macrophages
part of monocyte macrophage system - monocyte is precursor. In connective tissue, lungs, lymphoid organs, bone marrow
where do monocytes develop
bone marrow - then go to blood and then CT where they become macrophages
function of macrphages
lysosomes and lysosomal enzymes, phagocytosis, kill tumor cells, secrete cytokines, component of immune system to present to T cells
lymphocytes
develop in bone barrow and then circulate. differentiate into plasma cells (from B lymphocytes)
b lymphocytes become
plasma cells that make antibodies
lifespan of b lymphocytes vs plasma cells
lymphocytes long lived (1-2 yrs), plasma cells 2-3 weeks
other name for antibodies
immuglobulins
neutrophils staining
multilobed (at least 3), slightly pinkish cytoplasm with barely visible granules
neutrophil function
for acute infection, phagocytic cells with lysosomal enzymes
defunct neutrophils are
pus cells
eosinophil
bilobed, for parasitic infections and allergy reaction
basement membrane composed of
laminin, entactin, type IV collagen, GAGs
