ghh supportive tissue

General Histology and Histotechnique (1st semester; 2012-2013)

SUPPORTIVE TISSUE

(Specialized Connective Tissue)

I. Cartilages

- From chondrocytes

- Fibers: Collagen and Elastic

- Chondroitin Sulfate – for resilience

Ability to return to its

original shape.

- No blood vessels or nerves except in

perichondrium.

A membrane of dense irregular

connective tissue that surrounds

most of the cartilages.

- Can endure considerable stress

Due to the presence of fibers.

Types of Cartilage:

1. Hyaline Cartilage

- Most abundant type of cartilage

- Consists of bluish-white-ground substances with

collagen fibers.

- Surrounded by perichondrium

- Chondrocytes within Lacunae.

- Weakest type

- Chondrocytes forms in the perichondrium move

out of the cell and into the tissue where they

are scattered.

Ex. Trachea

Functions:

- It provides smooth surfaces for the movement

of joints.

- Provides support and flexibility.

Location: End of long bones, anterior ends of ribs,

nose part of larynx, trachea, bronchi, bronchial

tubes, and embryonic tissues.

2. Fibrocartilage

- Consists of chondrocytes that are scattered

- Strongest type

Combines strength and rigidity

- No perichondrium

- Symphysis – point where hipbones joint

anteriorly

- Menisci – the cartilage pads of the knee

- Periosteum – contains collagen

Ex. Bone Marrow

Function: For support and Fusion


Location: Pubic symphysis, Intervertebral discs,

Menisci of knee, and portions of Tendons that

insert into cartilage.

3. Elastic Cartilage

- Consists of chondrocytes located in the thread-

like collagen fibers.

- With perichondrium

Functions:

- Gives support and maintain shape

- Provide strength and elasticity

Location: External ear, auditory tubes, and lid on

top of Larynx.

Growth and repair of cartilage:

- Grow slowly

- Relatively inactive tissue

- When injured or inflamed, repair proceeds

slowly since it is avascular.

Two basic patterns of cartilage growth:

1. Interstitial growth

- Increases rapidly

Due to the existing division of

chondrocytes

- Expansion from within

Due to the existing chondrocytes that

is continuously dividing.

- Occurs while the cartilage is young and pliable.

From Childhood to adolescence.

2. Appositional growth

- Activity of cells in the inner chondrogenic layer

of the perichondrium leads to growth.

- Starts later that interstitial growth and

continues through adolescence.

- Fibroblast divide, some differentiate into

chondroblasts

- Chondroblasts surround themselves with matrix

and become chondrocytes.

Steps:

1. Ridges in Periosteum create groove for

periosteal blood vessel.


2. Periosteal ridges fuse, forming an endosteum-

lined tunnel.

3. Osteoblasts in endosteum build new concentric

lamellae inward toward center of tunner,

forming a new osteon.

4. Bone grows outward as osteoblasts in

Periosteum build new circumferential lamellae.

Osteon formation repeats as new periosteal

ridges fold over blood vessels.

- Osteoblast initiates calcification or

mineralization.

Crystallization and

tissue hardening by

mineral deposits.

II. Bone or Osseus Tissues

- 65% of bone weight in calcium hydroxyapatite

(Calcium phosphate), calcium hydroxide,

calcium carbonate.

(65% - Calcium phosphate only)

- Contains Tropocollagen

Subunits giving the

bone elasticity and

fracture resistance.

- Highly vascular and well innervated

- Contains lymph channels

- Functions in mineral storage and blood cell

production.

Bone

- Connective tissue components:

1. Periosteum

- Covering the bone

- Tough sheet of dense irregular connective

tissue surrounding the bone surface

2. Endosteum

- Inner part; Membrane that lines the space

within the bone that stores the yellow bone

marrow.

3. Red bone marrow

- Produces RBC, WBC’s, Platelets

- Process: Hematopoietic/hemopoiesis


4. Yellow bone marrow

- Consists primarily of adipocytes

- Infused scattered blood cells.

Functions of bones:

1. Support

- Framework for soft tissue

- Provide attachment pint of the bones

2. Protection

- Protect many internal organs of the body

Ex. Skull – brain; ribcages – lungs, heart

3. Assistance in movement

- During muscle contraction, it will pull the bone

in order to assists movement.

4. Mineral homeostasis

- Bone stores minerals (Ca2PO4, Ca2C03)

5. Blood cell production

- From red bone marrow

6. Triglyceride storage

- Yellow bone marrow to adipocytes

Four types of cells in bone tissue:

1. Osteogenic cells

- Develops into osteoblasts; desired

mesenchyma.

- Unspecified stem cells derived from

mesenchyme

- Only bone cell to undergo cell division

Location: Inner portion of the Periosteum in

endosteum, and in canals without bone that

contain blood vessels.

2. Osteoblasts

- Bone building cell

- Secrete collagen fibers and other substances

needed to build matrix of bone.

- Initiates calcification

3. Osteocytes

- Maintains bone tissue, mature cell

- Principal cells of bone tissues

Function:

Maintain the daily cellular activities of the bone

tissue.

Exchange of

nutrients and waste

in the blood.

4. Osteoclasts

- Contains a powerful lysosomal enzymes that

digest protein and mineral components of

underlying bones

- Functions in resorption, the breakdown of bone

matrix.

Ruffled border – deeply folded plasma membrane.


Huge cell – derived from fusion of 50 monocytes

contain in the endosteum.

Structure of bone macroscopic anatomy

1. Diaphysis

- The bone’s body or shaft which is a long-

cylindrical main portion of the body.

2. Epiphysis

- Proximal and Distal epiphysis – ends of bones.

3. Metaphysis

- Epiphyseal plate

- Part of the bone where diaphysis joins the

epiphysis and diaphysis.

- Includes epiphyseal line

- A point where cartilage is replaced by bone

- Hyaline cartilage that allows the diaphysis to

grow in length but not in width.

4. Articular

- Thin-layer hyaline cartilage covering the

epiphysis.

- It is where articulation with another bone

forms.

- Reduces friction and absorbs shocks at freely

removable joints.

5. Periosteum

- Outer covering

- Tough covering of dense tissues

- Contains the bone forming cells, osteocytes,

that in enables the bone to grow in diameter

but not in length

Functions:

- Protects the bone

- Assists in fracture repair

- Helps nourish bone tissue

- Serves as attachment point for ligaments and

tendons.

6. Medullary cavity/ Marrow cavity

- A space within diaphysis that contains the fatty-

yellow bone marrow

7. Endosteum

- Membrane containing bone forming cells and

line the medullary cavity.

Types of bone tissues:

I. Compact bone tissue

- Osteon or haversian system:

1. Concentric Lamellae


- Concentric ring of matrix that consists of

minerals with CaPO4, CaOH, CaCO3; more on

Calcium and Phosphate.

- Contains fiber-collagen – for strength

- Haversian – 20-40

2. Lacunae (Lacuna)

- Small spaces between lamellae that contains

the osteocytes.

3. Canaliculi

- Small canals that project from lacuna.

Provide route or blood for the

nutrients and oxygen

4. Haversian canal

- Volmann’s/Perforating canal

- Contain 1 or 2 blood vessels/nerves

- Connected with one another and communicate

with the free surfaces and bone marrow via the

perforating canal.

For movement of

nutrients system.

5. Interstitial System

- Contains in the interstitial system/Lamellae

Angular fragments of lamellar bone

Made up of the interstitial lamellae.

- Fragment of older osteons that have been

partially destroyed during bone rebuilding.

6. Cement lines

II. Spongy bone tissues

- Does not contain true osteon.

- Consist of trabeculae

Lamellae that are arranged in an

irregular columns of bones.

Function: Reduces weight

Ossification – process of bone formation

- Spaces between lamellae are filled with red

bone marrow


- It is light which reduces the overall weight of

bone.

Bone formation:

Ossification

Two kinds:

1. Intramembranous ossification

- Formation of bone directly on within fibrous

connective tissue membranes

- Formed by condensed mesenchymal cells

- Form directly from mesenchyma without first

going through a cartilage stage.

Steps:

1. Development of ossification center

2. Calcification

Osteocytes need to deposit mineral salts

so that it will harden matrix.

3. Formation of trabeculae

Fused with one

another that create

the spongy bone.

- Blood vessels – grow into spaces of spongy

- Development period: Spongy and compact

bone tissue.

4. Development of Periosteum

Fibrous collagen

- layer – Osteogenic layer

Layer under

Periosteum.

2. Endochondral ossification

- The formation of bone within hyaline cartilage

- Mesenchymal cells are transformed into

chondroblasts, which initially produce a hyaline

cartilage model of the bone

- Subsequently, osteoblasts gradually replace the

cartilage with bone.

Steps:

1. Development of cartilage model.

- Consists of hyaline cartilage and perichondrium

2. Growth of cartilage model

Two growths:

a. Interstitial growth

- Continuous cell division/growth from within.

b. Apositional growth


- Addition of more matrix by new chondroblasts

(grow in diameter).

3. Development of primary ossification center

- Nutrient artery stimulates Osteogenic cells to

differentiate onto osteoblasts

- Include the formation of primary ossification

center.

A region where bone tissue replaced

most of the cartilages.

4. Development of medullary (marrow) cavity.

- it is done by osteoclast that breaks the newly

formed spongy bone trabeculae

- Cavity filled with Blood vessels

5. Development of secondary ossification

center

- Secondary ossification

- As blood move upward into ossification plate.

6. Formation of articular cartilage and

epiphyseal plate.

- Hyaline cartilage that covers the

epiphyseal/epiphysis become the articular

cartilage but haversian canal is present in

between the epiphysis and diaphysis forming

the epiphysis.

Responsible for

lengthwise growth.

ghh supportive tissue

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