Kharkov National Medical University
CONNECTIVE TISSUE
Department of histology, cytology
and embryology
2013 medical students
CONNECTIVE TISSUE
• Connects other tissues, underlies or
surrounds them.
• Produces and maintains many different
intercellular substances.
• Provides support and nourishment.
Connective Tissues
Classification：
Blood & lymph
Connective tissue proper :
Loose connective tissue
Dense connective tissue
Specialized
Cartilage & bone
Adipose tissue
Reticular tissue
Mucoid tissue
Pigment tissue
Note: All Connective Tissues
have:
Common origin -
•
from mesenchyme
•Common structure
Cells +
Extracellular
substance
•Common similar)
functions
•
Note: Connective Tissues contain a
high ratio of extracellular matrix to
cells.
•
extracellular matrix is mostly secreted
by cells, which are embedded in it.
•
extracellular matrix varies for different
tissues and provides their structural
and functional features.
•
Examples : the fluid part of blood
the hard part of bone,
the tough part of fascia,
the resilient part of cartilage.
Embryonic Connective Tissue
--- Mesenchyme
• Consists of cells and ground substance with
reticular fibers
• Gives rise to all types of Connective Tissues
Connective tissue cells:
• 1st group - Fixed cells (intrinsic) – stable
population:
• 1. fibroblast – main cells, produce fibers
• 2. adipocyte
• 3. reticular cell
• 4. pericyte
5. undifferentiated cells(adventitial,
perivascular – stem cell)
All arise from mesenchyme.
• 6. Pigment cell – is from neural crest.
Connective tissue cells:
• 2nd group - Mobile cells – are the blood
leucocytes.
Fibroblast is fiber forming cell
Mature fibroblast is called fibrocyte.
Adipocytes (fat cells)
function as store house,
mechanical support, conservation of body heat
.
Mobile cells = blood leukocytes
Macrophage
blood monocyte
ps
er
ph
lys
Plasma cell
B-lymphocyte
Mast cells = basophils
.
Other mobile cells:
• All types of T-lymphocytes
• Microphage = neutrophil
• Tissue eosinophil
Connective tissue proper
• Consists of cells and extracellular matrix,
including fibers and ground substance.
• Classified:
• as loose or dense
regular or irregular
Classification
• loose – has predominance of ground
substance
• dense – has predominance of fibers
• regular – fibers form parallel bundles
• irregular – fibers are disordered
• Loose (Areolar) is always irreguar CT
• Dense:
– Dense regular CT
– Dense irregular CT
Loose irregular connective
tissue (L.I.C.T.)
• Is the most distributed
• it contains blood vessels
The Cells and Fibers of L.I.C.T.
General components of matrix :
1. Fibers and
2. Ground substance – is a gel
containing:
• water, salts and
• 3 kinds of molecules containing
carbohydrates:
– glycosaminoglycan or GAG,
– proteoglycans and
– glycoproteins
Extracellular matrix (ECM)
Features of ground substance:
• Permeability
• Barrier to the penetration of bacteria
Hylauronidase is an enzyme produced
by WBC’s, sperm and some bacteria.
Injection of hyaluronidase can speed
the passage of drugs and fluid through the
tissue.
Types of C. T. Fibers
Three types of fibers
– Collagen fibers
• Strongest and most
abundant
Tensile strength > steel
– Elastic fibers
• “Yellow fibers”
• Long, thin, branching fibers
• Can stretch and recoil
– Reticular fibers
Fine collagenous fibers
Distribution of Connective tissue proper
(CTP )
CTP is widely distributed.
It forms the capsules of organs and thin septa
inside them.
It always underlines epithelia.
It contains blood vessels and through its ground
substance all nutrients and waste products
diffuse between the blood and parenchymal
cells of all other tissues and organs.
Connective tissue proper
Functions:
•
•
•
•
•
•
Mechanical support
Protection
Exchange of metabolites.
Homeostasis
Protection against infections
Repair after injury, plastic function
LCT:
protection against infections,
noxious agents:
Cooperation of blood and connective
tissue cells for:
• Local reaction - inflammation
• General immunological reaction
Repair after injury, plastic
function of LCT
• High regenerative capacity (fibroblast)
• Fibrous scar formation
• NOTE! LCT carries additional functions
Other types of Connective tissue
proper (CTP):
Dense Regular CTP
Dense Irregular CTP
Fibers are predominant elements
Dense Regular Connective Tissue
fibrocyte
• Collagen fibers form parallel bundles
• fibrocytes
tendons, aponeuroses
Tensile strength in one direction
Dense Irregular Connective Tissue
Fibrocyte
• Collagen fibers are irregularly arranged
• Tissue can resist tension from any direction
• Very tough tissue -- dermis of skin
Connective tissue specialised
Adipose:
• Location – deep to skin: sides, buttocks, breasts; padding around
eyeballs and kidneys
• Function – insulation, mechanical support, stores energy.
Reticular:
• Location – spleen, lymph nodes, bone marrow
• Function – supporting framework for haemopoietic organs
•Mucoid: umbilical cord, incompressible
Adipose Tissue