Connective tissue presentation lesson.ppt

histology

1. histology by.Dr.abdirahman
Gagajir
1

2. histology by.Dr.abdirahman
Gagajir
2

3. histology by.Dr.abdirahman
Gagajir
3

4. Connective tissue
oConnective tissues function primarily to
support the body and to bindor connect
together all types of tissue.
oThis tissue also provide a mechanical
framework (the skeleton) which plays an
important role in locomotion.

5. oThis mechanical function is important in
maintaining the form of the body, organs and
tissues.
oThe tissue derives its name from its function
in connecting or binding cells and tissues.
Connective tissue is composed of:
(a) cells
(b) extracellular matrix.

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oMatrix consists of:
1.connective tissue fibers
2.Ground substance
3.Tissue Fluid

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Cells of the connective tissue
1.Fibroblasts
2.Adipose cells
3.Macrophage or Histiocytes
4.Mast cells
5.Plasma cells
6.Leukocytes

8. Histiocyte: A tissue macrophage; the
class includes hepatic Kupffer cells,
alveolar macrophages, giant cells of
granulomas, osteoclasts, and dermal
Langerhans cells.

9. oThe extracellular material of connective
tissue, which plays a major role in the
functioning of the tissue, is the dominant
component of the tissue.
oThe dominance of the extracellular
material is a special feature that
distinguishes connective tissue from the
other tissues of the body.

10. oThe extracellular matrixis composed of :
1.protein fibers(collagen fibers, reticular
fibers, elastic fibers)
2.amorphous ground substance
3.tissue fluid(not preserved in histological
preparations). The amount of tissue fluid is
fairly constant and there is an equilibrium
between the water entering and leaving the
intercellular substance of the connective tissue.
In pathological conditions (traumatic injury,
inflammation) fluid may accumulate in the
connective tissue, a condition known as edema.

11. FUNCTIONS OF CONNECTIVE
TISSUE
1.Structural support
The connective tissues serve several functions,
of which the most prominent function is
structural supportto enable maintenance of
anatomical form of organs and organ systems.
Examples include the connective tissue capsules
surrounding organs (such as the kidney, lymph
nodes).

12. oThe loose connective tissue acts to fill the
spaces between organs.
oThe tendons (connecting muscles to bone)
and the elastic ligaments (connecting bones
to bones) are examples of specialized
orderly forms of connective tissue.
oThe skeletal tissues (cartilage and bone) are
special forms of connective tissue.

13. 2. Metabolic functions
oThe connective tissues serve a nutritive role.
All the metabolites from the blood pass from
capillary bedsand diffuse through the adjacent
connective tissue to cells and tissues.
oSimilarly waste metabolitesfrom the cells
and tissues diffuse through the loose
connective tissue before returning to the blood
capillaries.

14. oThe adipose tissue(especially that of the
hypodermis) serves as an energy storeand also
provides thermal insulation.
oSurplus calories can be converted into lipid and
stored in adipocytes.
3. Blood components and blood vessels
oThe hematopoietic tissues(blood-forming tissues)
are a further specialized form of connective tissue.
oThese include the myeloid tissue(bone marrow)
and the lymphoid (lymphatic) tissue.
oThe lining of the blood and lymphatic vessels
(endothelial cells) as well as the peripheral blood,
are also specialized forms of connective tissue.

15. 4. Defensive functions
oVarious components of the connective tissue
play roles in the defense or protection of the
bodyincluding many of the components of
the vascular and immune systems (plasma
cells, lymphocytes, neutrophils, eosinophils,
basophils, mast cells).

16. oThe various macrophages of the body are also
categorized as connective tissue cells.
oThese all develop from monocytes and are
grouped as part of the Mononuclear
Phagocyte Systemof the body.
oMacrophages are important in tissue repair as
well as defense against bacterial invasion.

17. Cell type Chief function
Mesenchyme Embryonic source of all connective tissue cells
Fibroblasts
Chondroblasts
Osteoblasts
Structural support
Plasma cells
Lymphocytes
Neutrophils
Eosinophils
Basophils
Mast cells
Macrophages
Defense and immune
Adipocytes Metabolic
Energy storage
Thermal insulation

18. Between cells and fibers.
oThe intercellular ground substance is an
amorphous, transparent material composed mainly
of glycoproteinsand proteoglycans, with a fairly
high water content, that participate in binding cells
to the fibers of connective tissue
oViscous clear substance that has a slippery feel
oIt acts as a lubricant and a barrier to the
penetration to the tissues by foreign particles.

19. oH+E staining: lost during preparation and appears
empty.
oGround substance: Proteglycans and Hyaluronic
acid
oProteoglycans: Proteins and Glucosamine glycans
oThe main proteoglycans consist of a core protein
associated with sulfated glycosaminoglycan's (GAGs).
The main GAGs include : chondroitin-4-sulfate,
chondroitin-6-sulfate, keratin sulfate, heparan
sulfate) and the non-sulfated hyaluronic acid.
oAll substances passing to and from cells must pass
through the ground substance.
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20. CONNECTIVE TISSUE FIBERS
Connective tissue fibers are composed of
structural proteins. The three main types of
fibers are:
1.collagen fibers
2.reticular fibers
3.elastic fibers.

21. Collagen fibers
oCollagen is the most abundant protein in the
body (up to 30% dry weight).
oThere are more than 12 different types of
collagen, though the most common types are
Types I to V.
oCollagen is synthesized by a wide number of cell
types (including: fibroblasts, osteoblasts,
Chondroblasts, odontoblasts, reticular cells,
epithelial cells, endothelial cells, smooth muscle
cells, Schwann cells).

22. oThe main amino acidsof collagen are:
1.glycine(33.5%)
2.proline (12%)
3.hydroxyproline(10%)
oThe amino acids, hydroxyprolineand
hydroxylysineare characteristic of collagen.
It is the only naturally occurring protein with
both these amino-acids.

23. Collagen type Main sites Special features
Type I Bones, tendons, organ
capsules, dentin
Most abundant,
Typical collagen fibers
(64nm banding)
Type II Hyaline cartilage
Elastic cartilage
Very thin fibrils
Type III Reticular fibers ,smooth
muscle,arteries,uterus
,liver,spleen,kidney and
lungs
Often associated with Type I
Type IV Basal lamina associated
with epithelial and
endothelial cells
Amorphous (non-
fibrous)
Type V Basal lamina associated
with muscle
Amorphous (non-
fibrous)

24. oCollagen fibers consist of closely packed
orderly fibrils and when seen in bundles (as
in tendons, aponeuroses) appear white.
oIn histological preparations after regular
staining they are acidophilic (pink staining
with eosin).
oCollagen fibers are flexible, but very inelastic
with extremely high tensile strength.

25. Reticular fibers
oReticular fibers are very thin (diameters
between 0.5 -2m) and are not visible in
normal histological preparations after
regular staining (H & E), however they can
be visualized and stained black after
impregnation with silver salts.
oThis affinity for silver is called
argyrophilia.

26. oReticular fibers are also stained with the
PAS reactiondue to the high content of
glycoproteins associated with the fibers (6-
12% hexoses as opposed to 1% in
collagen fibers).
oIt is now recognized that reticular fibers
are a special form of collagen (Type III).

27. oReticular fibers form fine-meshed networks
around cells and cell groups.
oin diverse organs. They are abundant in
lymphatic organs (lymph nodes, spleen),
smooth muscle (in the sheath surrounding each
myocyte), in endoneurium (connective tissue
surrounding peripheral nerve fibers), and
supporting epithelial cells of several glands
(liver, endocrine glands).

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Reticular fibers

30. Elastic fibers
oElastic fibers, as the name suggests, are highly
elastic and stretch in response to tension.
oIn particular they are formed from the protein
elastin.
oThe amino acid composition of elastin, similar
to collagen, is rich in glycine and proline, but in
addition has two unusual amino acids,
desmosineand isodesmosine.
oElastic fibers also have a high content of
valine.

31. oElastic fibers are very prominent in elastic
tissues such as the elastic ligaments.
oWhen present in high concentration, the
elastin imparts a yellow color to the tissue.
The elastic laminae of arterial blood
vessel wallsare composed of a non-
fibrillar form of elastin.
oSites: Vertebral ligament, Larynx and
Elastic arteries.

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Elastic Fibers
Aorta is the example

33. CONNECTIVE TISSUE CELLS
Fibroblasts
oFibroblasts are the most common cell type
found in connective tissue.
oThe term "fibroblast" is commonly used to
describe the active cell type, whereas the more
mature form, which shows less active synthetic
activity, is commonly described as the
"fibrocyte".
oFibroblasts are elongated, spindle-shaped cells
with many cell processes.

34. oThey have oval, pale-staining, regular nuclei
with prominent nucleoli.
oAbundant rough endoplasmic reticulum and
active Golgi bodies are found in the cytoplasm.
oFibroblasts synthesize collagen, reticular and
elastic fibers and the amorphous extracellular
substance (including the glycosaminoglycans
and glycoproteins).

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FIBROBLASTS
oFusiform shaped
oMost common connective tissue cell
oProduces Collagen
i.Reticular fibers
ii.Elastic fibers
iii.Extra cellular matrix

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FIBROBLASTS

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Fibroblasts
Fusiform cell with elliptical nuclei

38. Macrophages
oMacrophages show pronounced
phagocytotic activity.
oThis can be demonstrated following injection
of vital dyes such as trypan blue or Indian ink
and the uptake of the particulate matter.
Macrophages originate from monocytes (from
precursor cells in bone marrow), which migrate
to connective tissue and differentiate into
tissue macrophages.

39. othe various macrophages of the body are
grouped in a common system called the
MononuclearPhagocyteSystem(MPS).
oA wide range of macrophages are included in
the MPS and include : Kupffer cellsof the
liver, alveolar macrophagesof the lung,
osteoclasts, microgliaetc.

40. oThe main functions of macrophages are
ingestion by phagocytosisof microorganisms
(bacteria, viruses, fungi), parasites, particulate
matter such as dust, and they also participate in
the breakdown of aged cells including
erythrocytes.
oThe intracellular digestionoccurs as a result of
fusion of lysosomeswith the phagosome
(ingested body).
oof the foreign body and sites of inflammation

41. oMacrophages are normally long-lived and
survive in the tissues for several months.
oIn some cases where a foreign body (such as a
small splinter) has penetrated the inner tissues
of the body, several macrophages may fuse
together to form multinuclear foreign body
giant cells.
oThese large cells accumulate at sites of
invasion.

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Macrophages /Histiocytes
oResembles Fibroblasts
oPhagocytic
oIngests Bacteria, cell debris and other
foreign matter

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MACROPHAGE

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MACROPHAGE

45. Mast cells
oMast cells are oval or round cells (20-30m
diameter) in connective tissue characterized by
cytoplasm packed with large round basophilic
granules(up to 2m diameter).
oThe granules are stained metachromatically
(purple after toluidine blue staining).
oTwo of the main components of mast cell
granules are histamineand heparin.

46. oThe granules of mast cells are released in
inflammatory responses.
oMast cells are abundant in loose connective
tissue (especially adjacent to blood vessels), in
the dermis, and in the lamina propria of the
respiratory and digestive tracts.

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MAST CELL
oSphericalto round
oSites: CT of Skin, Digestive tract and respiratory tract
oFunctions: Secrets Heparin and Histamine
Heparin is anticoagulant and Histamine is mediator of
inflammation

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Mast cell

49. Plasma cells
oare responsible for antibody production.
oThese large cells have eccentric nuclei, basophilic
cytoplasm (much rough endoplasmic reticulum
associated with protein synthesis) and well-
developed Golgi bodies.
oPlasma cells are relatively short-lived (10-20 days)
and are found in sites of chronic inflammation or
sites of high risk of invasion by bacteria or foreign
proteins (such as the lamina propria of the
intestinal and respiratory tracts).

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oSites :Respiratory and Digestive tract
oArises from Lymphocytes
oFunctions: Secretes antibodies into
circulation
Participate in the defense
mechanism

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Plasma cell
Almost oval shape and large, offset nucleus with chromatin
clumped in a "clockface" pattern, and an adjacent pale patch of
clear cytoplasm.

52. Leukocytes
oThe white blood corpuscles are commonly
found in connective tissue.
oThey migrate from the blood vessels to the
connective tissue, especially to sites of injury or
inflammation.

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oNeutrophils: Bacterial invasion
oEosnophils: Allergic reaction
oBasophils:Heparin and
histamines
oLymphocytes: Defense
oMonocytes: Defense

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Adipose cells
oSingle or in groups
oForms adipose tissue
oFunctions: 1. stores fat
2.Protective packing material

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Classification of Connective
tissue
1.Connective tissue proper
2.Specialized Connective Tissue
3.Supportive Connective Tissue

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Classification of Connective
tissue proper
1.Loose Connective tissue
2.Dense connective tissue
irregular
Regular

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Specialized Connective tissue
oAdipose tissue
oBlood
oBone
oCartilage
oLymphatic tissue
ohaemopoetic tissue

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Supportive Connective tissue
1.Cartilage
2.Bone

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Loose connective tissue
(Cellular Connective tissue)
oAbundance of cells
oLoosely arranged fibers
oAbundant Ground Substance
Sites: Beneath the epithelia that line the
internal surfaces of the body.

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Fibroblasts seen in plenty

63. Dense Connective Tissue
•Dense irregular connective tissue(variable
orientation of fibers)
•Dense Regular connective tissue( Fibers are
arranged in orderly manner)
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64. Dense Irregular Connective
tissue
oAbundance of fibers and few cells
oSparse cell population
oProvides significant strength(note high content
of collagen fibers)
oSites: Submucosa in the intestinal part Skin
Dermis.
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Dense irregular connective
tissue
Note the skin with irregular connective tissue

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Tendon
Note the arrangement of regular pattern
with Fibroblasts

67. Dense Regular Connective
Tissue
oOrderly and densely packed arrays of fibers
and cells.
eg: Tendons, ligaments and
aponeurosis
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CARTILAGE

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Cartilage basics
oSpecial form of connective tissue
oMain function is to support soft tissues
oConsists of cells and matrix
oMatrix contains collagen(Type 2) or elastic
fibers which gives the cartilage firmness
and resilience.
oCartilage exhibits tensile strength, provides
structural support and allows flexibility
without distortion.

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oCells: Chondrocytes
oHighly specialized ECM
oAvascular
oMatrix is solid and firm.
oGlycosaminoglycans in the matrix permits
diffusion of substances.
oHyaluronic acid makes it well adapted for
weight bearing capacity(Synovial joints)

72. Cartilage Matrix(GAG)
oHyaluronic acid
oChondrotin Sulfate
oKeratan Sulfate
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Hydrated matrix explains the resilence of the
cartilage

73. Classification
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1.Hyaline
2.Elastic
3.Fibrocartilage

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Hyaline Cartilage
Homogenous matrix, small nests of chondrocytes,
surrounding perichondrium
Lacunae

75. Sites
oArticular surface of bones
oCostal cartilages
oTrachea
oNose
oLarynx
oBronchus
oEmbryo: Skeletal model for most bones
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Elastic cartilage
Numerous elastic fibers

78. Sites
oExternal Ear
oAuditory Tube
oEpiglottis
oLarynx
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Fibrocartilage

81. Sites
oIntervertebral Disc
oSymphisis Pubis
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83. Growth of cartilage
oAppositional growth(From perichondrium)
oInterstitial growth(From division of
chondrocytes within their lacunae)
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84. Bone
oSpecialized form of connective tissue
oCells, fibers and matrix
oMineralized
oProvides attachment
oProvides protection
oHaemopoesis/reservoir of ca and P
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85. Types of Bone
1.Osteoprogenitor cells/Mesenchyme
2.Osteoblasts/Immature bone cells
3.Osteocytes/ Main cell
4.Osteoclasts/ large multinucleated
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86. oOsteons or haversian systems(structural
unit of bone between internal and
external circumferential lamellae)
oLamellar arrangement
oLacunae
oCanaliculi
oCentral( Haversian Canals)
oPerforating ( Volkmann's canal)
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