Histology of Connective Tissues
Connective
Tissues
Embryonic
Connective
Tissues
Mesenchymal
Connective Tissue
Mucoid
Connective Tissue
Loose Connective
Tissues
Areolar
Connective Tissue
Adipose Tissue
Connective
Tissues of Special
Purposes
Dense Connective
Tissues
Reticular
Connective Tissue
Dense Regular
Connective Tissue
Dense Irregular
Connective Tissue
Elastic Connective
Tissue
Cartilage
Bone Tissue
Hyaline Cartilage
Fibrocartilage
Elastic Cartilage
Blood
Types
Mesenchyme
Embryonic Connective Tissues
Histological Findings
Specialized Cells

Location
 Under the skin of
developing feotus
 Around blood vessels in
the adult
Function
 Form other type of CT

Mucous Connective
Tissue

Location
 Umbilical cord
Function
 Support
Irregular shaped
mesenchymal cells
Ground substance of
reticular fibers

Widely scattered Fibroblasts 
o Spindle-shaped cells
 Ground substance is
viscous, jelly-like
appearance (Wharton’s
jelly)
o Containing Collagenous
fibers
Mesenchymal cells
Fibroblast
Histological Appearance
Loose Connective Tissues
Histological Findings
Specialized Cells
Types
Areolar Connective Tissues
Location
 Subcutaneous layer of skin
 Lamina Propia of mucous
membrane
 Around
o Blood vessels
o Nerves
Function
 Strength
 Elasticity
 Support

Interspersed cells
o Fibroblast
o Adipocytes
o Macrophages
o Plasma cells
o Mast cells
 Semi fluid ground substances
with fibers
o Collagen (reddish in color and
thick)
o Elastin (darkly stained)
o Reticular
Adipose Tissue
Location
 Subcutaneous layer of skin
 Around heart and kidneys
 Yellow marrow
 Behind eye balls
 Pading around joints
Function
 Reduces heat loss
 Energy reservoir
 Supports and protects

Reticular Connective Tissue
Location
 Stroma
 Red marrow
 Reticular lamina of
basement membrane
 Around blood vessels
Function
 Supports
 Barrier
 Production of myeloid
lineage


Adipocytes
o Large
o Centrally located
droplects of fat
o Peripherally located
nuclei
Networks of interlacing
Reticular fibers with
Reticular cells
Numerous Myeloid Stem
Cells (stained darkly red)
Subcutaneous of
skin
o Histiocytes
 Lungs
o Alveolar
macrophages
 Nerves
o Microglial cells


Adipocytes

Reticular cells
Histological Appearance
Dense Connective Tissues
Histological Findings
Specialized Cells
Types
Dense Regular
Connective Tissue
Location
 Tendon and ligaments
 Aponeurosis
Function
 Provides strong
attachment between
various structures

Dense Irregular
Connective Tissue
Location
 Fascia
 Periosteum
 Pericardium
 Perichondrium
 Heart valves
Function
 Provides strength

Elastic Connective Tissue
Location
 Wall of Elastic artery
 Respiratory tracts
 Vocal cords




Consists of numerous fibers
which is arranged in
ORDERLY manner
o Collagenous fibers
With Fibroblasts in between
arranged in rows
(Fibrocytes in mature
tendon)

Fibroblasts
Consist mostly Collagenous
fibers arranged
DISORDERLY
With RANDOMLY located
Fibroblasts

Fibroblasts
Wavy bands of Elastic fibers 
(darkly stained) and
branching in all directions
Fibroblasts may present in
between
Fibroblasts
Histological Appearance
Connective Tissues with Specialized Functions
Cartilages
Histological Findings
Specialized Cells
Types
Hyaline Cartilage
(Marble hard)
Location
 Ends of long bone
 Cartilagenous ring of
respiratory tract
 Fetal skeleton
Function
 Smooth surface for joint
movement
 Flexibility
 Support

Elastic Cartilage
(Rubber-like)
Location
 Epiglotis
 Nose
 Ear auricle
 Eustachian tube
Function
 Supports
 Maintain shape

Fibrocartilage
(In Between)
Location
 Pubic symphasis
 Intervertebral disk
Function
 Support
 Fusion


Outer layer
o
Perichondrium which is Dense
Irregular CT
Inner layer
o
Chondrogenic area (not visible)

Spindled shape cells of
Chondroblasts
o
Young cartilage

Single oval Chondrocyte in
lacunae
o
Mature Cartilage

Lacunae

Isogenous group of cells (5-6
cells)

Highly basophilic territorial matrix
(due to GAG)

Interterritorial matrix
 Fibers are INVINSIBLE due to high
concentration of GAG
Inner layer
o
Chondrogenic area (not visible)

Spindled shape cells of
Chondroblasts
o
Young cartilage

Single oval Chondrocyte in
lacunae
o
Mature Cartilage

Lacunae

Isogenous group of cells (1-2
cells)

Less basophilic territorial matrix
(due to GAG)

Interterritorial matrix
o
Elastin fibers are clearly VISIBLE due to
lesser concentration of GAG
Lacunae
o Isogenous group of cells
(3-4 cells)
 Fairly visible collagenous
and elastic fibers


Histological Appearance
Chondroblasts
Chondrocytes
Skin layer
Subcutaneous layer
Elastic Cartilage
Connective Tissues with Specialized Functions
Histological Findings
Specialized
Histological Appearance
Cells
Types
Bone
Location
 Compact bone
 Spongy bone
Function
 Support
 Protection
 Storage (marrow)
 Movement
Lamellae
o Outer circumferential (not
seen)
 Below Periosteum
o Inner circumferential (not
seen)
 Before Endosteum
o Interstitial
 In between the Osteon
 Osteons
o Haversian canal in the middle
o Volksman’s canal runs
longitudinally (connecting the
Haversian canal)
o Lacunae and canaliculi for
Osteocytes
o Cementing line between the
lacunae



Osteoblast
Osteoclast
Connective Tissues with Specialized Functions
Blood
Histological Findings
Histological Appearance
Types
Red Cells
Function
 Gas carrying through
Heamoglobin
Haemoglobin (Hb)
 Fetal Hb
o HbF (100%)
 2 alpha
 2 gamma
 Adult
o HbA 1 (96%)
 2 alpha
 2 beta
o HbA 2 (2%)
 2 alpha
 2 delta
o HbF (2%)
 2 alpha
 2 gamma
Platelets
Function
 Heamostasis


Anucleated (NO NUCLEUS) and NO organelles, to give
more space for Haemoglobin (therefore considered to
be Post-cellular structure)
Pallor in the center, indicating biconcave in shape
Formation
 Induced by Erythropoietin (EPO) from Peritubular
capillary of the Kidneys
 Pluripotent Hemopoeitic Stem Cell –> CFU-S –> BFU-E –>
CFU-E –> Basophilic Erythroblast –> Polychromatophilic
Erythroblast –> Orthochromatophilic/Eosinophilic
Erythroblast –> ejection of nucleus –> Reticulocyte –>
Erythrocyte
Smooth disk in shape
Anucleated (NO NUCLEUS), therefore considered to be
post-cellular structure
 Contains several organelles
Formation
 Induced by Thrombopoietin from Liver
 Pluripotent Heamopoeitic Stem Cell –> CFU-S –>CFUMeg–> Megakaryoblast –> Promegakaryocyte –>
Metamegakaryocyte –> Megakaryocyte –> Platelets
Megakaryocytes (in the Red Marrow)
 Huge polyploidy cell
 Multinucelated with dispersed chromatin
 Numerous basophilic granules
 Numerous cytoplasmic blebs


Types
Neutrophils
Function

PMN, phagocytic
cells
Connective Tissues with Specialized Functions
Granulocytes
Histological Findings
Histological Appearance





Light pink cytoplasm
Lack of specific granules
Multilobulated nuclei, 2-3 lobes
Dark blue nucleus
The most abundant in leukocytes in the blood
Formation
 Induced by Colony Stimulating Factor release by marrow cells
 Pluripotent Heamopoeitic Stem Cell –> CFU-S –> CFU-GM –> CFU-G
–> Myeloblast –> Promyelocyte –> Neutromyelocyte –> Stab cells –
> Neutrophils
Basophils
Function

Stimulates
hypersensitivity
Eosinophils
Function
 Stops
hypersensitivity
 Helminthic
infection



Large amount of granules, they even compressed against its cell
membrane giving its angular appearance
The granules are stained by hematoxylin (BLUE) – acidic in nature
Basophil is the rarest leukocytes found in a normal blood smear
Formation
 Induced by Colony Stimulating Factor released by marrow cells
 Pluripotent Heamopoeitic Stem Cell –> CFU-S –> CFS-basophil –>
Myeloblast –> Promyelocyte –> Basophil myelocyte –> Basophil
metamyelocyte –> Stab cell –> Basophil




Contained numerous pinkish or reddish-orange granules
Azurophilic granules also present
Bilobed nucleus, makes it looks like a sausage with nuclear
projection linking the two lobes
Eosinophil is one of rarest leukocytes found in the normal blood
smear
Formation


Induced by Colony Stimulating Factor released by marrow cells
Pluripotent Heamopoeitic Stem Cell –> CFU-S –> CFU-Eosinophil –>
Myeloblast –> Promyelocyte –> Eosinophil myelocyte –> Eosinophil
metamyelocyte –> Stab cell –> Eosinophil
Neutrophil
Types
Lymphocytes
Connective Tissues with Specialized Functions
Agranulocytes
Histological Findings
Histological Appearance

Function
 T cell
o T helper Cell (CD4+)
 Induce the
formation of
Antibody and
memory cells by B
cell
o T cytotoxic Cell (CD 8+)
 Killed tumor and
viral-infected cells
 B cell
o Produce Antibody and
memory cells
o Once entered the
tissue will be called as
Plasma cells

Monocytes

Function
 Will form the
Mononuclear
Phagocyte System

Contained a very huge nucleus located at the
center of the cell
Due to the huge size of nucleus, the cytoplasm is
somehow pushed to the periphery giving its
distinctive shape of a blue rim
The nucleus has a dense heterochromatin
Formation
 Produce in red marrow, mature in Thymus
 Pluripotent Heamapoeitic Stem Cell –> CFULymphocyte –> CFU-Lymphocyte T/Lymphocyte B
–> T/B lymphocyte –> T/B lymphoblast –> T/B
Lymphocyte

The largest blood cell in the circulating
bloodstream
Nucleus is accentric, kidney shaped, and having
coarse chromatin network
Formation
 Produce and mature in red marrow
 Pluripotent Heamopoeitic Stem Cell –> CFU-S –>
CFU-GM –> CFU-Monocyte –> Promonocyte –>
Monocyte
 Once enter the tissue it will form MACROPHAGE