CONNECTIVE TISSUE
(C.T.)
Dr.Mohammed Shamiah

connective tissue
٢


The mesodermal ………………. to mesenchymal
tissue (undifferentiated mesenchymal cells &
hemogenous intercellular substance of proteins)
The mesenchymal tissue are differentiated in the
embryo into:
1- Connective tissue C.T.
2- Vascular tissue
3- Smooth muscle
Dr.Mohammed Shamiah
٣
-FUNCTIONS OF CONNECTIVE
TISSUE:




Providing structural support .
Serving as a medium for exchange.
Aiding in the defense and protection of the body .
Forming a site for storage of fat .
Dr.Mohammed Shamiah
٤

The connective tissue formed of:
A- C.T. Cells
B- C.T. Fibers
C- C.T. Matrix
Dr.Mohammed Shamiah
Types of C.T.
٥


According to the nature of intercellular matrix :
We have 3 types of
1- C.T. proper
2- Cartilage
3- Bone
connective tissue
( soft matrix)
(rubbery matrix)
( solid matrix)
Dr.Mohammed Shamiah
1-Connective Tissue Proper
٦

It is called connective because is support, binds
& connection various tissue and organs.
Dr.Mohammed Shamiah
The C.T. Proper is formed of:
٧

1- C.T. cells.

2- C.T. fibers.

3- Soft matrix or ground substance.
Dr.Mohammed Shamiah
-Types of C.T. Proper:
٨
 The cells & C.T. fibers are present in
the soft C.T.
1-Areolar C.T.
2-Yellow elastic C.T.
3-Mucoid C.T.
4-White collagen C.T.
5-Adipose C.T.
6-Reticular C.T.
Dr.Mohammed Shamiah
Types of Connective tissue cells:
٩
A) Fixed C.T. cells:
1.
Fibroblast
2.
Fixed macrophages
3.
Fat cells
4.
Mesenchymal cells
5.
Pericyte cells
6.
Endothelial cells
7.
Reticular cells

1.
2.
3.
4.
5.
B) Free C.T. Cells:
Mast Cells
Plasma Cells
Free Macrophages,
Blood Leucocytes
Melanophore Cells
Dr.Mohammed Shamiah
1-Fixed C.T. cells as:
١٠
1.
Fibroblast & Fibrocytes Cells:
 Develop from mesenchymal cells &
pericytes.
 It is very numerous in areolar C.T.
 Dark basophilic cytoplasm.
 The cytoplasm is rich in RNA, ER, GA,
Mitochondria.
 Fibroblast can divide.
 Fibroblast can changes into myofibroblasts.
Dr.Mohammed Shamiah
LM of fibroblasts (arrows)
١١
Dr.Mohammed Shamiah
Functions of Fibroblast:
١٢
1- Form collagen, elastin & reticulin substances in
order to form C.T. fibers.
2- Form the mucoprotein of the C.T. matrix.
3- Increase number during healing of wounds.
4- Fibroblast change into myofibroblasts which can
close wounds.
Dr.Mohammed Shamiah
Fibrocytes === mature fibroblasts
١٣



Small spindle-shaped cells with dense nuclei.
Light basophilic cytoplasm.
Can not divide.
Dr.Mohammed Shamiah
2- Fixed macrophages or histiocytes cells
١٤






Derived from blood monocytes.
More present in the damaged C.T.
Have irregular cell membrane.
Cytoplasm is not clear-rich in lysosomes.
The nucleus is small, kidney shape.
Histiocytes cells can be stained with vital stain as
trypan blue.
Dr.Mohammed Shamiah
Functions of histiocytes cells :
١٥
- Defense mechanism of the body.
- Can engulf (eat) foreign bodies, bacteria and old
blood cells.
- Can clean wound from foreign bodies & debris.
- Can transport antigens.
- Macrophage may be collected with each other to form
Multinucleated Giant Cell in which enclose large
foreign bodies in order to destroy them.
Dr.Mohammed Shamiah
3-Adipose cell or fat cells or adipocytes:
١٦





-
Derived from mesenchymal cells
Flat peripheral nucleus
There are 2 types of fat cells:
1-Unilocular white fat cells.
2-Multilocular brown fat cells.
Fat cells can not divide.
Stained :
Orange with Sudan III.
Black with Sudan black- Osmic acid.
Dr.Mohammed Shamiah
Adipocytes (fat cells)
١٧
Dr.Mohammed Shamiah
Functions of adipocytes :
١٨
1.
2.
3.
4.
Brown fat regulate body temperature in newborn
infants.
White fat cells release energy during starvation.
Support organs as kidney.
They act as heat insulator.
Dr.Mohammed Shamiah
4-The Mesenchymal Cells(UMC):
١٩
- Embryonic branched cells called (UMC).
- Has large oval nucleus & basophilic cytoplasm.
- Present in bone marrow to give blood cells, also in
C.T. & around blood vessels.
- Function:
Can differentiate into other types of C.T.
Dr.Mohammed Shamiah
5-The Pericyte cells:
٢٠



Pale branched cells (peri= around).
Present immediate external to the endothelium of
blood vessels capillaries & small venules.
Considered as mesenchymal cells which persist in
adult life.
Dr.Mohammed Shamiah
 Function of Pericyte :
٢١
- Give rise to both fibroblast & smooth muscle cells.
- Role in the process of healing of connective tissue &
blood vessels.
- Modified to form myoepithelial cells which can
contract.
Dr.Mohammed Shamiah
6- The Endothelial Cells:
٢٢
- Present in the surface of blood capillaries
& blood vessels.
- They form the endothelium of blood vessels.
- Develop from the embryonic mesenchymal cells.
Dr.Mohammed Shamiah
- Functions of Endothelial Cells :
٢٣
1- Synthesize (Type 4) collagen .
2- Can divide to form new capillaries in tissue injuries.
3- Can form the basement membrane of the
endothelium.
4- Divide rapidly giving rise to secretory endothelial
cells of lung capillaries to secret angiotensin
converting enzyme.
Dr.Mohammed Shamiah
7- Reticular Cells:
٢٤



Present in mainly in the reticular C.T.
Modified fibroblast which are specialized to
secrete reticular fibers.
Reticular cells are found in the stroma of bone
marrow, lymph nodes, spleen, liver & pancreas.
Dr.Mohammed Shamiah
- Function of Reticular Cells:
٢٥



Supportive & phagocytic cells.
Form the stroma of glands & bone marrow.
Removal cellular debris from the lymphatic tissues.
Dr.Mohammed Shamiah
2- Free C.T. Cells:
٢٦
1- Mast Cells.
2- Plasma Cells.
3- Free Macrophages.
4- Blood Leucocytes.
5- Melanophore Cells.
Dr.Mohammed Shamiah
1-Mast Cells
٢٧


Small cells, round, irregular in shape.
Present in groups blood vessels.
Types of mast cells:
1-Heparin secretory mast cells
- Present in the C.T. of skin, secret heparin which is an
anticoagulant.

Dr.Mohammed Shamiah
٢٨
2-Histamine secretory mast cells:
- Present under mucosa of respiratory &digestive tract.
- Histamine can contract smooth muscle.
- Dilated blood vessels capillaries.
- Increased the capillary permeability.
Dr.Mohammed Shamiah
TEM of a Mast
Cell
٢٩
Dr.Mohammed Shamiah
- Functions:
٣٠
Secrete heparin, histamine & serotonin.
(Paracrine cells)


Release an immediate hypersensitivity factors which
activate defense system of the body.
Dr.Mohammed Shamiah
2- Plasma Cells:
٣١



Present in the C.T. of the peritoneum, submucosa of
digestive, respiratory tract, lymph nodes & spleen.
Originate from plasmablast cells which develop from
B-lymphocytes
Small & round with homogenous basophilic cytoplasm.
Dr.Mohammed Shamiah
Functions of Plasma Cells :
٣٢
1.
2.
3.
Secrete specific antibodies against organisms &
foreign bodies antibodies circulate in the blood
termed (humoral antibodies) & processes is called
humoral immunity.
Can not divide.
Have no phagocytic activity.
Dr.Mohammed Shamiah
3- Free Macrophages:
٣٣



Derived from blood monocytes after their migration
to C.T.
Their cytoplasm is rich in lysosomes & RER.
They have oval eccentric nuclei.
Dr.Mohammed Shamiah
Functions of Free Macrophages :
٣٤
1.
2.
3.
4.
Immune system of the body.
They are highly phagocytic cells.
Secrete collagenase & elastase enzymes &
lysosome.
Kill certain viruses through secretion of interferon.
Dr.Mohammed Shamiah
4- Blood Leucocytes:
٣٥

Appear normally in the C.T. of the following body
organs:
1- Eosinophils & Basophils:
- Found in C.T. of respiratory intestinal & female genital
tract.
- They increase in allergic conditions.

Dr.Mohammed Shamiah
٣٦
- Lymphocytes & Monocytes:
 Present in the C.T of many organs.
 Increased in number in case of chronic infections.
- Neutrophils:
 They migrate from blood vessels to C.T. where acute
infection is present in order to phagocytose
microorganism.
Dr.Mohammed Shamiah
LCT – M = mast cell; P = plasma cells; F = fibroblasts;
Eo = eosinophils, N = neutrophils
٣٧
Dr.Mohammed Shamiah
5-Melanophore pigment cells
٣٨




They are C.T. macrophages which phagocytose
melanin Pigments are formed by the melanocytes.
Melanophores are branched cells with small round
nuclei.
Melanophore are rich in melanin pigments.
Present in the C.T. of skin & eye.
Dr.Mohammed Shamiah
Functions:
٣٩


They carry melanin pigments.
Protect skin from sun and facilitate eye vision.
Dr.Mohammed Shamiah
٤٠
Thank you
Dr.Mohammed Shamiah