Group 3 - Connective Tissue

7/31/2019 Group 3 - Connective Tissue

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CONNECTIVE TISSUEGROUP 3


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WHAT IS CONNECTIVE TISSUE?

is a diverse group of tissues

derived from embryonic mesenchyme

it forms an extensive compartment in the body, can beconsidered as the "glue" that holds the body together

Specialized connective tissue :

(adipose tissue; cartilage; bone; blood and hematopoietictissue )

consists of individual cells scattered within an

extracellular matrix.

Ground substance Fibers


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ADIPOSE

HYALINE ELASTIC FIBRO

CARTILAGE


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BONE

SPONGY

3 Neutrophils & 1Basophils

BLOOD

COMPACT

Eusinophil & FewPlatelets

MONOCYTES LYMPHOCYTE


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THE GROUND SUBSTANCE

The translucent material in which the cells andfibers of connective tissue are embedded.

Major polysaccharides

Glycosaminoglycans

a class of macromolecules that arelong, linear polymers ofdisaccharide. Major GAGs

Condroitin sulfate

Keratan sulfate

Heparan sulfate

Hyalunoric acid


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FIBERS

TYPES : collagen fibers

reticular fibers

elastic fibers


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COLLAGEN FIBERS

most common fiber type

collagen fibers are seen to be made up of thread-likesubunits called

present in all kinds of tissue These are flexible fibers with a high tensile

strength

collagen fibrils.


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COLLAGEN FIBERS


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COLLAGEN FIBERS

12 TYPES :

TYPE I

TYPE II

TYPE III

TYPE IV

TYPE V

TYPE VI

TYPE VII

TYPE VIII

TYPE IX

TYPE X

TYPE XI

TYPE XII


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COLLAGEN FIBERS

TYPE I the most ubiquitous

fibers are flexible but offer great resistance to tension

occuring in the Dermis

Bone

Tendon

Fascia

In the capsules of organs


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this specimen shows the appearance of type i collagen

fibers under the electron microscope. these fibers show

a characteristic banding pattern which results from theoverlap of the tropocollagen constituents. the periodicity

of this pattern is typically 64 nanometers.
http://medcell.med.yale.edu/histology/connective/collagen_fibers_em.phphttp://medcell.med.yale.edu/histology/connective/collagen_fibers_em.phphttp://medcell.med.yale.edu/histology/connective/collagen_fibers_em.phphttp://medcell.med.yale.edu/histology/connective/collagen_fibers_em.php


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COLLAGEN FIBERS

TYPE II :Forms very thin fibrils that are embedded in ana

bundant ground substance found in the :

Hyaline

Elastic cartilage Nucleus pulposus of the intervetebral discs

Vitreous body of the eye


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COLLAGEN FIBERS

TYPE III :Forms argyrophilic fibers called reticular fibers

abundant in:

Loose connective tissue walls of blood vessels

stroma of various glands

Spleen

Kidney Uterus


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COLLAGEN FIBERS

TYPE IVSpecialized form largely restricted to the basal lamina of

epithelia

TYPE V

Widespread occurrence but is present only in very smallamounts

TYPE VIPresent in small amounts at most sites where types I & III

are found

TYPE VII assoc. w/ the basal lamina of many epithelia but is most

abundant at the dermo-epidermal kunction of the skin


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COLLAGEN FIBERS

TYPE VIII Secretory product of endothelial cells growing in vitro ,sometimes called

endothelial collagen Major component of descemets membrane, the typical basal lamina of

the corneal epithelium

TYPE IX Found mainly in cartilage

TYPE X Confined to cartilage Found in the matrix immediately surrounding hypertrophic

chondrocytes involved in endochondral bone formation TYPE XI

Associated with type II collage in cartilage

TYPE XII


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RETICULAR FIBERS

They provide a supporting framework for thecellular constituents of various tissues andorgans


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FIBRILLIN

is defective or deficient in MARFANSYNDROMEA heritable disease of connective tissue,

characterize by excessively long arms & legs & a

progressive dilatation of the ascending aorta thatmay lead to fatal rupture.


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ELASTIC FIBERS

give tissue the ability to cope with stretch and distension.

interwoven w/ collagen fibers to limit distensibility & toprevent tearing.

2 large amino acids unique to elastin

Desmosine isodesmosine

2 structural components

Elastincauses collagen to coil in a random way

Microfibrils

consist of a fibrillar glycoprotein

In developing elastic tissue, they appear before the elastin, and arebelieved to serve as an organizing structure for it.


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ELASTIC FIBERS


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ADHESION GLYCOPROTEINS

It is the attachment of other cell types.

Examples of adhesion glycoprotein are:

Fibronectin

Laminin Thrombospondin

They have binding sites for cell membrane and for collagen.

FUNCTION: maintain adhesion of cells to their substrate.

they also influence the state of differentiation of the cells.


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FIBRONECTIN

is a high-molecular weight (~440kDa)glycoprotein of the extracellular matrix thatbinds to membrane-spanning receptor

proteins called integrins.

It is synthesized by connective tissue

fibroblasts because it is not directly visible bymicroscopy.
http://en.wikipedia.org/wiki/Integrinshttp://en.wikipedia.org/wiki/Integrins


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FIBRONECTIN

It has long flexible fibronectin molecule forcell-binding, and collagen-binding domainsalong its length.

connecting the surface of the cells to the fibrousand amorphous components of the extracellularmatrix.

PLASMA FIBRONECTIN synthesized by the liver cell and endothelial cells.

Binds to fibrin and may have a significant role in bloodclotting


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LAMININ

Has a molecular weight of one (1) million.

It is a trimeric proteins that contain an -chain, a -chain, and a -chain, found in five,four, and three genetic variants, respectively.

It is a cross-shaped molecule with rod-likeand globular regions.


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It is synthesized by connective tissuefibroblast.


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THROMBOSPONDIN

Is an adhesive glycoprotein of 450,000 MW

First identified as a product of activatedplatelets, secreted during blood clotting.


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ORIGIN OF CONNECTIVE TISSUE FIBERS

Connective tissue fibers are produced byfibroblast. large, flat, branching cells which appear spindle-

shaped in a side view.

Connective tissue fibers are composed ofstructural proteins. The three main types offibers are: collagen fibers reticular fibers elastic fibers


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CELLS OF CONNECTIVE TISSUE


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CELLS OF CONNECTIVE TISSUE (CATEGORIES)

Fixed Cells these are relatively stablepopulation of long-lived cells that include thefibroblastsecrete and maintain the

extracellular components and adipose cellsthat store and release lipids to be used as anenergy source in the metabolism of other

cells throughout the body.


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CELLS OF CONNECTIVE TISSUE (CATEGORIES)

Free cellsare a changing population ofmotile cells that enter the connective tissuefrom the blood and wander through its

ground substance.

Most of these are short lived and are

continually replaced from the large pool ofcells of the same type circulating in theblood.


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MESENCHYMAL CELLS

The connective tissues develop from theembryonic tissue called mesenchyme.

Mesenchymal cells are small fusiform orstellate cells not easily distinguised fromfibroblasts.


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MESENCHYMAL CELLS


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FIBROBLAST

These are cells that produce the extracellularcomponents of developing connective tissue.

When they become relatively inactive in fiber

formation , some histologist prefer to callthem fibrocytes.


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FIBROBLAST


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FIBROCYTES

The shape of these cells depends , to someevents, on the nature of their substrate.

They are usually deployed along bundles of

collagen fibers and appear in sections,as afusiform cells with long tapering ends.


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FIBROCYTES


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FIBROBLAST (FUSIFORM)


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FIBROBLAST


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FIBROBLAST


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ADIPOSE CELLS

Adipose cells or fat cells are fixed cells of theconnective tissue specialized for thesynthesis and storage of lipid.


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ADIPOSE CELLS


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ADIPOSE TISSUE (WHITE FAT)


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MACROPHAGES

Also known as the histiocytes.

It plays a role in the maintenance of normaltissues by ingesting dead cells and cellular

debris and other particulate matter andbreaking them down with their lysosomalenzymes.


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MACROPHAGES


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MACROPHAGES


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MACROPHAGES(CATEGORIES)

Free macrophages motile cells of varyingshape that wandered through the groundsubstance.


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MACROPHAGES (CATEGORIES)

Fixed macrophages sessile cells that werestretched out along collagen fibers and had ashape not unlike that of fibroblast.


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FREE CELLS OF

CONNECTIVE TISSUE


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Monocytes are rarely found in connectivetissue for, on leaving the bloodstream.

They respond to chemotactic metabolicproducts of bacteria by congregating at thesite.


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Phagocytes must be derived from bone

marrow stem cells, have a characteristicmorphologic features, and exhibit relativelyintense phagocytic activity mediated byimmunoglobulin or serum complement.


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Metchnikoff proposed the termmacrophage system.

Aschoff suggested the termreticuloendothelial system.

Van Furth introduced the term

mononuclear phagocyte system.


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Neutrophils are rarely found in normalconnective tissue but they are included here,among its free cells.

Endothelial Cell Adhesion Molecule-1 (ELAM-1)makes their lumenal surface sticky.

Leukocyte adhesion molecules (LeuCAMs)

promote their adhesion to the sticky capillary

endothelium.


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EOSINOPHIL LEUKOCYTES

Eosinophils are normal constituents of theconnective tissue.

They are numerous in the connective tissueof the nasal cavity, lungs, skin and laminapropria of the intestine than they areelsewhere.

Eosinophil Cationic Protein (ECP)appears to be incorporated in themembrane of the target parasite.


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Lymphocytes which are the principalagents of the immune system, found in

small numbers in the connective tissuethroughout the body.

They function in protective immuno-surveillance against the rich bacterial flora inthe lumen of the gut.

Endothelial cell adhesion molecules(also called addressins or selectins) serve

as homing receptors binding lymphocytes. Two kinds of Lymphocytes:

T-lymphocytes

B-lymphocytes


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Plasma Cells are few in number inconnective tissues in most areas of

the body. Responsible for thesynthesis of the antibodies found inthe bloodstream.


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Mast Cells are the largest of the free cells ofthe connective tissue and are easily identifiedby the numerous basophilic granules in theircytoplasm, which may obscure the nucleus.

- oval to round connective tissue, whosecytoplasm is filled with basophilic granules.

Basophils are smaller and usually have abilobed nucleus. They are found only in theblood and, like other granular leukocytes.


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The major cavities of the body are lined byserous membrane:

The peritoneumlining of the abdominal cavity,and the pleuralining the thoracic cavity.

Consist of a thin layer of typical looseconnective tissue covered by mesothelium. Mesothelium a squamous epithelium of

mesodermal origin. Thin sheet-like. Omentum a large free fold of visceral

peritoneum that hangs, like a curtain.


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VARIANT TYPES OF LOOSE CONNECTIVE TISSUEReticular Connective Tissue

Mucous Connective Tissue


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RETICULAR CONNECTIVE TISSUE

- cells tend to be stellate with slender radiatingprocesses

- they are NOT considered to be a distinct celltype, but merely FIBROBLASTS

- forms the stroma of the bone marrow andthat of the spleen, lymph nodes and thymus


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MUCOUS CONNECTIVE TISSUE

- very large amount of amorphous groundsubstance that is rich in hyaluronic acid

- rare in adults, but common in the embryo

- principal component of the umbilical cord,called Whartons jelly


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DENSE CONNECTIVE TISSUE

Dense Irregular Connective Tissue

Dense Regular Connective Tissue


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DENSE IRREGULAR CONNECTIVE TISSUE

- collagen fibers

- free cells are very few

- found in the dermis of the skin; capsules ofthe spleen, liver, and lymph nodes; tunicaalbuginea of the testis; the dura mater of thebrain; and sheaths of large nerves


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DENSE REGULAR CONNECTIVE TISSUE

- flat sheets of closely approximated coarsecollagen fibers

- tendons


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HISTOPHYSIOLOGY OF CONNECTIVE TISSUE

NORMAL FUNCTIONS

MechanicalSUPPORT

EXCHANGEof metabolites

STORAGEof energy reserves in adiposecells

PROTECTIONagainst infection

REPAIRafter injury


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INFLAMMATION

- invasion of tissues by microorganismstriggers a local response of the connectivetissue

- redness, swelling and pain


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EFFECTS OF HORMONES

- influenced by sex hormones

Protein synthesis by fibroblasts aresuppressed

Permeability of capillaries is decreased

Lysosomal membranes of phagocytes arestabilized

Lymphocytes are destroyed


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REPAIR

- they not only heal defects in the connective

tissue but also respond to injury to othertissues that have little capacity for repair


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CONNECTIVE TISSUE DISEASE

1. Ehlers-Danlos Syndrome

2 Osteogenesis Imperfecta


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2. Osteogenesis Imperfecta

3 Lathyrism


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3. Lathyrism

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Group 3 - Connective Tissue