PART 2:
Connective
Tissue
 Histology
is defined as the study of the
microanatomy of animal and plant tissues

A tissue is a group of like cells of similar
specialized structure which carry out similar
specific functions.
A
tissue is a group of like cells of similar
specialized structure which carry out
specific functions.
 Groups of tissues compose and work
together to form organs.
 All organs are composed of two or more
types of tissues.
 There are four major tissue types:
1. Epithelial
2. Connective
3. Muscle
4. Nervous
Locations:
 Found
everywhere in the body
 Includes the most abundant and
widely distributed tissues
Functions
 Binds
body tissues together
 Supports the body
 Provides protection
i.
iii.
iv.
Connective tissues get their name because
they attach or hold different tissue types
together.
Produce materials which they secrete in
their extracellular space to form the
extracellular matrix
Extracellular matrix:

Non-living material that surrounds living
cells
Often the cells are very scattered about
and few in number.
iv. This is why some connective tissues
take long periods of time to heal when
damaged (cartilage and bone).
v. Variations in blood supply
 Some tissue types are well vascularized
 Some have a poor blood supply or are
avascular
iii.
vi.
The matrix varies depending on the connective
tissue type.
 Bones: are hard, solid, crystalline structure
 Cartilages: flexible
 Tendons and ligaments: composed of protein
fibers
 Dermis of skin: sponge-like rich in
 Adipose: soft
 Plasma of blood: liquid
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
Loose irregular connective tissue
Loose reticular connective tissue
Adipose tissue
Dense regular connective tissue
Dense irregular connective tissue
Hyaline cartilage
Elastic cartilage
Fibrocartilage
Bone
Blood
Name: Loose irregular connective
B. Structure: Areolar tissue has a gel like
matrix with cells called fibroblasts
 Fibroblasts:
 produce two types of protein fibers,
collagen (larger) and elastin (small
thread-like).
 Areolar:
 Soft, pliable tissue like “cobwebs”
A.
B.
Location:
 Most widely
distributed connective
tissue
 Around the organs,
under mucus
membrane epithelial
and surrounding
capillaries.
B.
Functions:
 Functions as a packing
tissue
 Holds and conveys
tissue fluid.
 Can soak up excess
fluid (causes edema)
Mucosa
epithelium
Lamina
propria
Elastic
fibers
Collagen
fibers
Fibroblast
nuclei
Fibers of
matrix
Nuclei of
fibroblasts
(e) Diagram: Areolar
Photomicrograph: Areolar connective tissue, a
soft packaging tissue of the body (300×).
Figure 3.19e
A.
B.
C.
Name: Loose reticular connective
tissue
Structure: Has a network of
collagen reticular fibers, which
have a netted arrangement.
Location: This tissue composes the
spleen, the lymph nodes, and the
bone marrow.
d.


Function:
These fibers form a soft internal
skeleton (stroma) that supports other
cell types,
Particularly erythrocytes (red blood
cells) and leukocytes (white blood
cells
Spleen
White blood cell
(lymphocyte)
Reticular
cell
Blood
cell
Reticular fibers
Reticular
fibers
(g) Diagram: Reticular
Photomicrograph: Dark-staining network
of reticular connective tissue (430×).
Figure 3.19g
A.
B.
Name: Adipose tissue
Location: under the skin, around the
kidneys, heart, within the abdomen, and
breasts of females
C.
D.
Structure:
 Matrix is an areolar tissue composed of
collagen and elastin fibers
 Adipocytes (fat cells) are present:
large cells with their nuclei pushed to
the side by large lipid (fat) deposits
Functions:
 Insulates the body
 Protects some organs
 Serves as a site of fuel storage
Nuclei of
fat cells
Vacuole
containing
fat droplet
Nuclei of
fat cells
Vacuole
containing
fat droplet
(f) Diagram: Adipose
Photomicrograph: Adipose tissue from the
subcutaneous layer beneath the skin (430×).
Figure 3.19f
Name: Dense regular connective
tissue (dense fibrous tissue)
B. Structure:
 Main matrix element is collagen
fibers tightly packed together.
 Some elastin fibers are present.
 Fibroblast (cells that make fibers)
are present
A.
C.
Locations:
 Tendons—attach skeletal
muscle to bone
 Ligaments—attach bone to
bone at joints
 Dermis—lower layers of the
skin
D.
Functions:
 Can withstand great pulling
force when it is applied in one
direction.
 Attaches muscles to bone or
muscles to muscles.
Ligament
Tendon
Collagen
fibers
Collagen
fibers
Nuclei of
fibroblasts
Nuclei of
fibroblasts
(d) Diagram: Dense fibrous
Photomicrograph: Dense fibrous connective tissue
from a tendon (500×).
Figure 3.19d
 Dense
Regular: 2:22
 https://www.youtube.com/watch?v=y_mjSk5
TE1E
Name: Dense irregular connective
B. Structure:
 Matrix is primarily composed of
collagen and elastin fibers
irregularly arranged (not
parallel).
 Fibroblast are the cells present
and produce the matrix
A.
Location: in the dermis of the skin,
the submucosa of the digestive
tract and the fibrous capsules
surrounding certain joints and
organs.
B. Function:
 This tissue is able to withstand
tension or stress exerted in many
directions.
 Also provides structural strength.
A.
 Cartilage





General Structure:
Cartilage is a connective tissue which has
qualities between dense connective tissue
and bone.
Cells called chondroblasts secrete the
matrix.
When the cells mature they are trapped
within cavities called lacunae.
These mature cells surrounded by matrix
are called chondrocytes
Avascular and lacks nerve fibers
 There
are three types of cartilages
and they differ in the composition of
their matrix:
1. Hyaline cartilage
2. Elastic cartilage
3. Fibrocartilage
Name: Hyaline cartilage (most common
type of cartilage in body)
B. Structure:
 The matrix is amorphous (without any
particular shape) and rubbery
 Has a network of collagen fibers present
that are not visible.
 It appears bluish white and glassy (semitranslucent)
A.
Location:
 At the end of long bones
 Forms the cartilages of the rib
cage, nose, trachea, and larynx
(Adam’s apple)
 Entire fetal skeleton prior to birth
D. Function:
 Support, reinforcement,
cushioning, and resistance to
compressive stress
C.
 In
a young child the
majority of the
appendicular skeleton is
composed of this type
of cartilage which is
eventually replaced by
bone tissue as the child
matures.
Chondrocyte
(Cartilage cell)
Chondrocyte
in lacuna
Lacunae
Matrix
(b) Diagram: Hyaline cartilage
Photomicrograph: Hyaline cartilage
from the trachea (500×).
Figure 3.19b
Name: Elastic cartilage
B. Structure:
 The matrix is similar to hyaline cartilage –
amorphous with collagen fibers
 BUT the matrix is rich in elastin fibers
which are visible and usually stain dark
purple.
C. Location: It is located in the pinna (outer
ear) and the epiglottis of the throat.
A. Function: This cartilage maintains the shape
of a structure while allowing great flexibility.
A.
Name: Fibrocartilage
B. Structure:
 The matrix of this cartilage is less
firm than that of hyaline cartilage
 has many thick, visible collagen
fibers present
C. Location: intervertebral discs, the knee
and the pubic symphysis.
D. Function: the absorption of
compressive shock
A.
Chondrocytes
in lacunae
Chondrocites in
lacunae
Collagen fiber
Collagen
fibers
(c) Diagram: Fibrocartilage
Photomicrograph: Fibrocartilage of an
intervertebral disc (110×).
Figure 3.19c
 Hyaline
Cartilage: 4:27
 https://www.youtube.com/watch?v=PVoz28_
n0uU
 Elastic Cartilage: 1:58
 https://www.youtube.com/watch?v=1rgtmJN
Lwn0
 Fibrocartilage: 1:48
 https://www.youtube.com/watch?v=imDyTw
vgNaQ
Name: Bone or Osseous tissue
B. Structure:
 Bone tissue matrix is secreted by cells
called osteoblasts.
 The matrix is composed of collagen
fibers and calcium (hydroxyapeptite
crystals).
 The bone matrix is constantly being
broken and reabsorbed by cells called
osteoclasts.
A.
C.
Structure (cont’d):
 The
cells which are in the lacunae and
surrounded by the matrix are called
osteocytes.
 The bone tissue is highly vascularized
and has nerve fibers present.
 The blood vessels and nerve supply are
located in tunnel-like structures which
run through the matrix called Harversian
Canals.
Bone cells in
lacunae
Central canal
Lacunae
Lamella
(a) Diagram: Bone
Photomicrograph: Cross-sectional view
of ground bone (300×).
Figure 3.19a
Function:
 Support, protection,
 Provides levers to which muscles
act on to produce movement,
 Storage of calcium, phosphorous,
and other mineral
 The marrow inside the bone is the
site of blood cell production
C.
Name: Blood
B. Function: transport of nutrients
and the removal of waste from the
body’s tissues
C. Structure:
 Blood is composed of formed
elements (cells) suspended in a
fluid matrix called plasma.
 Fibers are visible during clotting
A.
Structure (cont’d):
 There are three types of formed elements,
each with a specific function.

Erythrocytes or red blood cells function in
the transport of oxygen.

Leukocytes or white blood cells are
involved with our body’s defense against
infection.

Thrombocytes or platelets are actually
fragments of cells which are involved in
blood clot formation to prevent blood
loss.
A.
Blood cells
in capillary
Neutrophil
(white blood
cell)
White
blood cell
Red blood
cells
Red
blood cells
Monocyte
(white blood
cell)
(h) Diagram: Blood
Photomicrograph: Smear of human blood (1300×)
Figure 3.19h
 Blood
Smear: 6:10
 https://www.youtube.com/watch?v=jJqHdwg
FH3c