Histology of connective tissue Flashcards
what does all connective tissues originate from
embryonic mesenchyme
developing mainly from mesoderm
What does connective tissues provide
Support
Binds tissues together
Protects tissues and organs of the body
3 main components of connective tissues
Cells
Protein fibres
Amorphous ground substance
What makes up amorphous ground substance
Proteoglycans
Glycoaminoglycans
Glycoproteins
What do the fibers and ground substance make up
Extracellular matrix
Classifications of connective tissues
Dense
Loose
Specialised
Dense
Regular and irregular
Loose
Areolar
Adipose
Reticular
Specialised
Blood
Lymph
Bone
Cartilage
Functions of connective tissues
Provides substance and form to the body and organs
Defends against infections
Injury repair
Cushion between tissues and organs
Stores lipids
Medium for diffusion
Attaches muscle to bone and bone to bone
Support
Loose areolar tissue
Forms layer beneath epithelial lining of many organs
Fills spaces between givers of muscle and nerve to provide support
Highly cellular with random collagen arrangement (some elastic and reticular)
Most numerous cells are fibroblasts
Numerous cells in loose connective tissues
Fibroblasts
Dense connective tissue overview
More collagen fibers with little ground substance and fewer cells (mainly fibroblasts)
Greater resistance to stretching
Poorly vascularised
Dense regular connective tissues
Mainly type 1 collagen fibers oriented in parallel direction
In tendons and ligaments
Dense irregular connective tissues
Collagen fibers woven in multiple directions
Resist tensile forces
Found in dermis
Types of fibers
Collagen
Elastic
Reticular
Collagen fibers
Most type one collagen, most abundant protein in body
Provide tensile strength, resistance to stretching
Elastic fibers
Contain elastin and fibrillin
Provide elasticity
Can be stretched but return to original length
Reticular fibers
Contain type 3 collagen
Provides support
Network of thin fibers
Type 1
Fibrils aggregate into fibers and fiber bundles
Most widespread
Forms component of extra cellular matrix/interstitial collagen, tendons, ligaments, capsules of organs
Type 2,
Fibrils don’t form fibers
Present in hyaline and elastic cartilages
Type 3
Fibrils aggregate into fibers
Present surrounding smooth muscle cells and nerve fibers
Forms strong of lymphatic tissues and organs
Type 4
Chemically unique form of collagen
Doesn’t form fibrils
Major component of basal lamina
what is in the image
elastic fibers
contain protein elastin along with lesser amounts of proteins and glycoproteins
after being stretched or compressed will return to original shape
first is in mesentery, dermis and then wall of aorta
what are elastic fibres composed of
elastin and fibrillin
which stain can view elastic fibres
H&E
what is in the image
reticular fibers
seen in lymph nodes
black fine lines
lymphoid cells stained red
which stain is used in reticular infers
by a silver impregnation method
argyrophilic
where are reticular fibres mainly located
in reticular tissue of soft organs such as liver and spleen
anchor and provide structural support to parenchyma
2 types of cells
fixed and transient
fixed cells overview
remain mostly stationary within connective tissue
perform functions where they are formed
fibroblasts, adipose cells
transient cells
free
originate mainly in the bone marrow and circulate in the bloodstream
leave to enter the connective tissue spaces to perform their specific functions
white blood cells: neutrophils, eosinophils, basophils, lymphocytes and monocytes
examples of fixed cells
chondrocytes
adipocyte
fibroblast
mesothelial cells
endothelial cells
osteocyte
examples of transient cells
t lymphocyte
plasma cells
osteoclast
macrophages
megakaryocyte
mast cell
neutrophil
eosinophil
basophil
b lymphocyte
what is in the image
fibroblasts
what is the most abundant type of cell in the connective tissue
fibroblasts
secrete ECM comp: collagen/elastin
types of fibroblasts
active
inactive
active fibroblasts
often reside close to type 1 collagen bundles
lie parallel to long axis of the fibers
elongated, fusiform cells possessing platelet staining cytoplasm
difficult to distinguish from collagen when stained with H&E
has a large darker stained granular ovoid nucleus with well defined nucleolus
inactive fibroblast
fibrocytes
smaller
more ovoid
nuclei are smaller and elongated
more deeply stained
do not manufacture ECM
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loose connectie tissue
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loose connective tissue
displays collagen and elastic fibre
under light microscope
what is in the image
dense regular connective tissue
sparse cytoplasm of fibroblasts not visible as blends with collagen fibres
is an image of a tendon
nuclei of fibroblasts appear as dark dots in rows between fibres
what is in the image
regular dense connective tissue
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irregular dense connective tissue
general organisation of loose connective tissue
much ground substance
many cells
little collagen
randomly distributed
major functions of loose connective tissue
supports microvasculature
nerves
immune defence cells
examples of loose connective tissues
lamina propria
general organisation of dense irregular connective tissue
little ground substance
few cells
much collagen in random fibres
major functions of dense irregular connective tissue
protects and supports organs
resists tearing
examples of dense irregular connective tissue
dermis of skin
organ capsules
submucosa
general organisation of dense regular connective tissue
almost completely filled with parallel bundles of collagen
few fibroblasts
aligned with collagen
major functions of dense regular connective tissue
stron connections within musculoskeletal system
strong resistance to force
examples of dense regular connective tissue
ligaments
tendons
aponeuroses
corneal stroma
2 types of adipose tissue
white
brown
what is in the image
unilocular
develops from embryonic mesenchyme with formation of lipoblasts containing small fat vacuoles
mature to adipocytes, storing fat
lipid-storing support cells
act as physical cushioning and padding
arborizing capillary vessels transfer metabolites to and from cells
what is in the image
brown adipose tissue
multilocular
most prominent in newborn
develops as cluster of eosinophilic cells
abundant mitochondria for heat generation
has lipid rich cells with central nucleus and polyhedral shaped cells with granular pink cytoplasm
capillary vascular supply with thin fibrocollagenous septa divides tissue into small lobules