Connective tissue the review

PRESENTED BYK.GOPALASATHEESKUMAR,

M.PHARM., [email protected]

1

CONNECTIVE TISSUE

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INTRODUCTION

COMPOSITION OF CONNECTIVE TISSUE

TYPES OF CONNECTIVE TISSUE

FUNCTIONS OF CONNECTIVE TISSUE

HISTOPATHOLOGY

STAINING OF CONNECTIVE TISSUE

REFERENCES

CONTENTS


INTRODUCTION


TYPES


Tissues

Types of tissues Epithelial tissue: protection, secretion, and absorption Connective tissue: support, bind, and protect organs Muscle tissue: contraction Nervous tissue: information to other cells

CONNECTIVE TISSUE

Connects, supports, binds, or separates different types of tissues and organs in the body

Develops from the mesoderm

Found in b/w other tissues everywhere in the body, including nervous system

INTRODUCTION


Mixture of cells

Fibers

Ground substanc

e

COMPOSITION


FIBROBLASTS

MACROPHAGES

MAST CELLS

PLASMA CELLS

LEUKOCYTES

ADIPOCYTES (FAT CELLS)

MIXTURE OF CELLS


FIBROBLASTS

Most common cells in connective tissue. Their nuclei are ovoid or spindle shaped and can be large or small in

size depending on their stage of cellular activity. Synthesis ECM and collagenMACROPHAGES

Highly phagocytic cells that are derived from blood monocytes. With conventional staining, macrophages are very difficult to identify

unless they show visible ingested material inside their cytoplasm.


MAST CELLS

Bone marrow origin and are distributed chiefly around small blood vessels.

They are oval to round in shape, with a centrally placed nucleus.

PLASMA CELLS

Derived from B lymphocyts They are oval shaped and have the ability to secrete antibodies

that are antigen specific.


LEUKOCYTES

White blood cells, are considered the transient cells of connective tissue. They migrate from the blood vessels into connective tissue by the process of

diapedesis.

ADIPOCYTES

Arise from undifferentiated mesenchymal cells of connective tissue. They gradually accumulate

cytoplasmic fat, which results in a significant flattening of the nucleus in the periphery of the cell.


Ground substance is a clear, viscous substance with a high water content, but with very little morphologic structure.

When stained with basic dyes (periodic acid-Schiff [PAS]), it appears amorphous, it appears as a clear space.

Its major component is Glycosaminoglycans (GAGs), which are long, un-branched chains of polysaccharides with repeating disaccharide units.

Most GAGs are covalently bonded to a large central protein to form larger molecules called proteoglycans.

GROUND SUBSTANCE


Collagen Elastic Reticula

r

FIBERS


Collagen COLLAGEN FIBERS are the most common and widespread

fibers in connective tissue. 25-35% of body The collagen molecule (tropo-collagen) is a product of the

fibroblast. Each collagen molecule is 300 nm in length and consists of

three polypeptide amino acid chains. Elastic Elastic fibers have a very resilient nature (stretch and recoil),

which is important in areas like the lungs, aorta, and skin. They are composed of two proteins, elastin and fibrillin, and

do not have a banding pattern.Reticular RETICULAR FIBERS are small-diameter fibers. Supporting mesh in soft tissues(liver,bone marrow and

lymphatic system)


Connective Tissue Proper

Specialized Connective

Tissues

Embryonic Connective

tissue

Supportive connective

Tissues

Fluid connective

tissue

TYPES OF CONNECTIVE TISSUE


CONNECTIVE TISSUE


Dense irregular

CT

Dense regular CTLoose CT

CONNECTIVE TISSUE PROPER


CONNECTIVE TISSUE PROPER


Dense irregular connective tissue is a cushion like tissue, which provides great strength against pressure-induced stresses on structures or organs.

“Dense” refers to the high abundance of collagen fibers (but fewer cells) compared to loose connective tissue.

“Irregular” indicates that the orientation of the fiber bundles is in many different directions (or randomly oriented bundles).

Contains mostly collagen fibers with a lesser number of other fibers such as elastic fibers.

The skin has a thick layer of dense irregular connective tissue, with fibers arranged in various directions to resist stretching forces in any direction.

It is prominent in the dermis of the skin, mammary glands, and capsules of many organs.

Function - provide strength.

DENSE IRREGULAR CT


This type of tissue is composed of coarse collagen bundles that is densely packed and oriented into parallel cylinders.

Long, thin fibroblasts are found among the fiber bundles and are oriented in

the same direction as the fibers.

The nuclei of the fibroblasts are visible, but the cytoplasm is not easily seen.

The thick bundles of collagen fibers fill the intercellular spaces.

Dense regular connective tissue provides resistance to traction forces in tendons and ligaments.

Function = provide strong attachment between various structures

DENSE REGULAR CT


Loose connective tissue is also called areolar connective tissue. This type of connective tissue has abundant ground substance,

with many connective tissue cells and relatively few fibers. It is richly vascularized, flexible, and not highly resistant to

stress. The lamina propria of the digestive tract is an extreme example

of loose connective tissue. This tissue lies immediately beneath the thin epithelium of the

gut, which is one place where the body’s defense mechanisms initially attack bacteria and pathogens.

Therefore, plasma cells, mast cells, leukocytes, and fibroblasts are common in this area.

Loose connective tissue is characterized by loosely arranged, woven connective fibers, abundant ground substance, and tissue fluid, which contains the rich array of connective tissue cells.

LOOSE CONNECTIVE TISSUE


Adipose connective tissue

Reticular connective tissue

Elastic connective tissue

SPECIALIZED CONNECTIVE TISSUES


Specialized Connective Tissues


Adipose tissue is a special form of connective tissue and has a rich neurovascular supply.

Adipocytes (fat cells) are scattered within a loose collagenous supporting tissue in this unilocular adipose tissue.

Each adipose cell contains a single large drop of lipid; it has a thin rim of cytoplasm around the lipid, and its flattened nucleus is located in the periphery of the cell.

Adipocytes are the primary site for storage of energy, and lipid deposition and mobilization are regulated by hormonal factors (steroids, insulin, thyroid hormone, etc.).

Adipocytes also play a role in the synthesis of some hormones such as leptin.

During childhood, the adipocyte numbers may increase depending on nutrition and other factors, but in adulthood, adipocyte numbers normally remain constant.

ADIPOSE CONNECTIVE TISSUE


Reticular tissue is a specialized loose connective tissue that provides a delicate supporting framework for many highly cellular organs, such as endocrine glands, lymphoid organs, the spleen, and the liver.

They are arranged in a net like framework to support parenchymal cells, in this example, pancreatic cells.

The inset drawing represents the organization of reticular fibers and pancreatic cells.

These fibers consist of collagen type III, which forms a mesh like network that supports the liver cells and holds these cells together.

There is a sinusoid running between the reticular fibers, which appears as empty space here.

RETICULAR CONNECTIVE TISSUE


Elastic connective tissue consists predominately of elastic material, and this allows distension and recoil of the structure.

This tissue can be found in some vertebral ligaments, arterial walls, and in the bronchial tree.

Thick bundles of elastic lamellae are arranged in parallel wavy sheets, with the smooth muscle cells and collagen fibers insinuated between alternating lamellae.

The elastic fibers are formed by elastin and fibrillin micro-fibrils. Elastic connective tissue is able to recoil after stretching. This property in large arteries helps to moderate the extremes of

pressure associated with the cardiac cycle. Abnormal expression of the fibrillin (FBN1) gene is associated

with abnormal elastic tissue disease.

ELASTIC CONNECTIVE TISSUE


Mesenchymal connective

tissue

Mucous connective

tissue

EMBRYONIC CONNECTIVE TISSUES

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EMBRYONIC CONNECTIVE TISSUES

24


Mesenchyme (mesenchymal connective tissue) is found in the developing structures in the embryo.

It contains scattered reticular fibers and mesenchymal cells, which have irregular, star or spindle shapes and pale-stained cytoplasm.

These cells exhibit cytoplasmic processes, which often give the cells a stellate appearance.

Mesenchymal cells are relatively unspecialized and are capable of differentiating into different cell types in mature tissue cells, such as cartilages, bones, and muscles.

These blood cells contain a nucleus in each cell. This is the characteristic of their immature state (a nucleated red blood cells are characteristic of the mature state and are found in adult tissues).

Interestingly enough, some vertebrates, such as frogs and chickens, have nucleated red blood cells in the adult state.

MESENCHYMAL CONNECTIVE TISSUE


An example of mucous connective tissue that has an abundance of a jellylike matrix with some fine aggregates of collagen fibers and stellate-shaped fibroblasts is shown.

It is found in the umbilical cord and sub dermal connective tissue of the embryo.

Mucous tissue is a major constituent of the umbilical cord, where it is referred to as Wharton jelly.

In this example, the viscous ground substance has been stained with a special stain to reveal jelly like mucin, which contains hyaluronic acid and glycoproteins.

Collagen fibers and large stellate-shaped fibroblasts (not mesenchymal cells) predominate in the mucous tissue.

MUCOUS CONNECTIVE TISSUE


BONE CARTILAGE

SUPPORTIVE CONNECTIVE TISSUE


Bone cells (osteocytes) are surrounded by a matrix of collagen fibres strengthened by inorganic salts, especially calcium and phosphate.

This provides bones with their characteristic strength and rigidity.

BONE


BONE

Compact bone – solid or dense appearance

Spongy or cancellous bone –’spongy’ or fine

honeycomb appearance.

TYPES OF BONE


Found on ends of long bone

Contains bony bars and plates called trabeculae separated by irregular spaces

Blood cells are made within the red marrow found in the spongy bone

SPONGY BONE


COMPACT BONE

Found in the outer portion of long bones

Consists of many cylindrical-shaped units called osteon


Cartilage has a flexible rubbery matrix.

It is found in organs like,

External ear

Tip of the nose or

The “Adam’s apple” (thyroid cartilage of the larynx).

CARTILAGE


TYPES OF CARTILAGE


Hyaline Cartilage Elastic Cartilage Fibrocartilage Hyaline cartilage is

named for its clear, glassy microscopic appearance.

surrounded by a sheath of dense irregular connective tissue.

locations: end of a rib to the breastbone, around the larynx, the fetal skeleton.Functions: Eases joint movements; holds airway open during respiration; moves vocal cords during speech , growth zones of long bones of children.

Elastic cartilage is named for its conspicuous elastic fibers.

surrounded by a sheath of dense irregular connective

tissue.locations: External ear; epiglottisFunctions: Provides flexible, elastic support.

Fibrocartilage for its coarse, readilyvisible bundles of collagen.locations: Pubic-symphysis, spinal column; menisci, or pads of shock-absorbing cartilage,knee joint.Functions: Resists compression and absorbs shockin some joints.

TYPES OF CARTILAGE


FLUID CONNECTIVE TISSUE


BLOOD Connective tissue composed

of cells suspended in liquid matrix called plasma

Red blood cells (erythrocytes) – carries oxygen

White blood cells (leukocytes) – fights infection

Platelets – fragment of giant cells found in bone marrow


Type Connective TissueCells

Main Locations Main Functions

Dense irregularconnective tissue

Predominantlyfibroblasts; otherconnective tissuecells occasionallypresent

Dermis of the skin,capsules of manyorgans

Resists stressfrom alldirections;protects organs

Dense regularconnective tissue

Predominantlyfibroblasts; otherconnective tissuecells occasionallypresent

Tendons, ligaments Providesresistance totraction forces

Looseconnective tissue

Fibroblasts,macrophages,adipocytes, mastcells, plasma cells,leukocytes

Lamina propriaof gastrointestinaltract; around thenerves and vessels(in adventitia layer)

Provides protection,suspension, andsupport; conduitfor vessels andnerves; environmentfor immunedefense function

Adiposeconnective tissue

Predominantlyadipocytes (fat cells);fibroblasts and otherconnective tissuecells occasionallypresent

Hypodermis of theskin, mammaryglands, and aroundmany organs

Providesenergy storage,insulation;cushioning oforgans; hormonesecretion

Types of connective tissue


Reticularconnective tissue

Fibroblasts,reticular cells,hepatocytes,smooth musclecells, Schwann cellsdepending on thelocation

Liver, pancreas,lymph nodes,spleen, and bonemarrow

Provides supportiveframeworkfor hematopoieticand parenchymalorgans

Elasticconnective tissue

Predominantlyfibroblasts orsmooth muscle cells;other connectivetissue cells occasionallypresent

Vertebral ligaments,walls of the largearteries

Provides flexiblesupport for thetissue; reducespressure on thewalls of theArteries

Mesenchymalconnective tissue

Mesenchymal cells Embryonicmesoderm

Gives rise to allconnective tissuetypes

Mucousconnective tissue

Spindle-shapedfibroblasts

Umbilical cord,subdermal layerof the fetus, dentalpulp of the developingteeth, nucleuspulposus of the disk

Provides cushionto protect theblood vessels inthe umbilical cord.


Providing a medium for oxygen and nutrients to diffuse from capillaries to cells.

Wraps around and cushions and protects organs

Stores nutrients

Internal support for organs

As tendon and ligaments, it protects joints and attaches muscles to bone and each other

Runs through organ capsules and in deep layers of skin giving strength

FUNCTIONS OF CONNECTIVE TISSUE


Fibroblasts are responsible for synthesis of various fibers and extracellular matrix components, such as collagen, elastic, and reticular fibers.

Macrophages contain many lysosomes and are involved in the removal of cell debris and the ingestion of foreign substances ; they also aid in antigen presentation to the immune system.

Adipocytes function to store neutral fats for energy or production of heat and are involved in hormone secretion.

Mast cells contain many granules, indirectly participate in allergic reactions, and act against microbial invasion.

Plasma cells are derived from B lymphocytes and are responsible for the production of antibodies in the immune response.

Lymphocytes participate in the immune response and protect against foreign invasion.

Neutrophils are the first line of defense against bacterial invasion. Eosinophils have anti-parasitic activity and moderate allergic reactions. Basophils have a (primary) function similar to mast cells; they mediate

hypersensitivity reactions.

FUNCTIONS OF THE CELLS IN CONNECTIVE TISSUE


HISTOPATHOLOGY


1 in 10 people have a connective tissue disorder

Congenital disease – Marfan syndrome Ehlers-Danlos syndrome Myxomatous degeneration – Pathological weakness Mixed connective tissue disease – Autoimmune disease Systemic lupus erythematosus(SLE) Scurvy – Vit-C – collagen synthesis

PATHOLOGICAL TERMS Urticaria: An itchy skin eruption Pruritis: Itching of the skin Cirrhosis: An abnormal liver condition Jaundice: Yellow staining of the skin Coagulopathy: A disorder that prevents the normal clotting process Necrosis: Irreversible cell changes that occur as a result of cell death

CONNECTIVE TISSUE DISORDER


Van Gieson’s stain- staining of collagen and other connective tissue

Masson’s trichrome stain- distinguishing cells from surrounding connective tissue

Mallory’s trichrome stain- examining the collagen of connective tissue

Aniline blue stain

Eosin- stain of blood cells

Reticulin stain- visualize reticular fiber

STAINING OF CONNECTIVE TISSUE


Human Anatomy second edition by Kenneth S. Saladin, “Histology: the study of tissues”. Anatomy& Physiology in Health and Illness 12th Edition by Ross and Wilson, “The cells,

tissues and organization of the body”. Fundamentals of histology by GP Verma, “Connective tissue”. Anatomy& Physiology for nurses by Inderbir Singh, “General connective tissue” Human anatomy & Physiology by Biology-about.com, “Connective tissue Types and

examples”. Biology Encyclopedia by Biologyreference.com, “Connective tissue”.

REFERENCES


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Connective tissue the review

Health & Medicine

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