Specialized Connective Tissue

Specialized Connective Tissue

• Cartilage and Bone

• Blood

Cartilage and Bone tissues

• special type of dense regular connective tissue

Cartilage

cells are called chondrocytes

Bones

ells are called osteocytes

Lacunae

Cartilage and bone tissues are both inside small cavities called ____

Gristle

Cartilage is also called ____

CARTILAGE

There are no blood or lymph vessels, no nerves

CARTILAGE

Chondrocytes are nourished by diffusion of nutrients from surrounding tissues

▪ Cartilage Cells (Chondrocytes)

▪ Cartilage Matrix

Composition of Cartilage

Isogenous cells (chondrocytes)

Young forms are elliptical and are capable of mitosis and producing ____

Chondrocytes (Cartilage Cell)

Mature forms are larger and rounded but do not divide by mitosis

Chondrocytes (Cartilage Cell)

Cytoplasm is finely granular and basophilic

Matrix

Consists of amorphous ground substance and extracellular fiber

Matrix

Ground substance is made up of water, proteoglycans and glycoproteins

Glycoproteins

promotes adherence of collagen fibers to the cell surface of chondrocytes

Cartilage formation (Chondrogenesis)

Cartilage arises from mesenchyme

Chondroblasts

Mesenchymal cells differentiate into osteoprogenitor cells ____ (growth and repair of cartilage)

Cartilage formation (Chondrogenesis)

Mesenchyme surrounding the developing cartilage compresses and differentiate into Perichondrium

Cartilage formation (Chondrogenesis)

Cartilage grow by interstitial growth and appositional growth

TYPES OF CARTILAGE

▪Hyaline Cartilage

▪Elastic Cartilage

▪Fibrous Cartilage

HYALINE

Most abundant type; forms the bulk of the skeleton (fetus in-utero)

HYALINE

Glistening, smooth and pearly white in fresh specimens

HYALINE

Composed of cells (chondrocytes) inside lacunae which are embedded in cartilage matrix composed of ground substance and extracellular fibers (Type II collagen fibers)

HYALINE

Chondrocytes vary in size and shape, Young forms are elliptical, and are capable of mitosis; daughther cells are called isogenous cells;

Mature forms are larger and rounded); with basophilic and finely granular cytoplasm; nucleus is ovoid

HYALINE

Exists only in limited areas in and around joints,the sternal end of ribs, some parts of respiratory system and external ear; tendons and ligaments

ELASTIC

More flexible than hyaline

ELASTIC

Yellowish in fresh specimens

ELASTIC

Morphologically similar to hyaline except that the matrix is less abundant; Aside from type II collagen fibers, elastic fibers are also present (account for pliability and yellowish color of the tissue)

ELASTIC

It is present in the auricle and external acoustic meatus of the ear, auditory tube, epiglottis, and some parts of larynx

FIBROUS

-Regarded as a transitional stage between dense regular and cartilage

-Can withstand greater stress than hyaline or elastic cartilage

FIBROUS

White in fresh specimens

FIBROUS

Composed of Type I collagen fibers

FIBROUS

Makes up the intervertebral discs, articular discs, and glenoid and acetabular labra, surface layers if tendons and ligaments

Perichondrium

Connective tissue that envelops all cartilages

Perichondrium

• Consists of Fibrous layer(outer) and chondrogenic layer (inner)

Perichondrium

• Chondrogenic layer is consists of stem cells called osteoprogenitor cells that can be transform into either chrondroblasts or osteoblasts

Degeneration

is possible, and most common is calcification of the matrix

Regeneration

is difficult and limited, damaged area in cartilage is invaded by scar tissue

BONE

• Comprise the bulk of the adult skeleton

BONE

• Protects vital organs

BONE

• Serves as levers for muscles

BONE

• Store houses for calcium and phosphorus

BONE

• Surrounded by periosteum which has osteocytes and little ground substance with dense mineralized matrix

Bone

Osseus tissue

BONE FORMATION

OSTEOGENESIS; OSSIFICATION

BONE FORMATION

Bone is produced to replace existing mesenchyme or hyaline cartilage

1) Intramembranous ossification
2) Endochondral or Intracartilaginous ossification

Bone formation occurs in two process

INTRAMEMBRANOUS OSSIFICATION

Ossification that occurs in areas occupied by mesenchyme

INTRAMEMBRANOUS OSSIFICATION

Type of ossification that produces most of the flat bones of the skull

-- eg. parietal and occipital bones

INTRAMEMBRANOUS OSSIFICATION

At the start of this process, the area of mesenchyme (referred as center of ossification) becomes highly vascularized; mesenchymal cells differentiate initially into osteoprogenitor cells, then into osteoblasts.

area of mesenchyme

referred as center of ossification

INTRAMEMBRANOUS OSSIFICATION

Mesenchyme that envelopes the developing bone differentiates into the periosteum, while the mesenchyme that surrounds each bone spicule differentiates into endosteum while the tissue that fills the spaces between the spicules transforms into myeloid or hemopoietic tissue

INTRACARTILAGINOUS OSSIFICATION

Involves replacement of a hyaline cartilage with bone

INTRACARTILAGINOUS OSSIFICATION

Ossification that forms cartilage bones, most of the bones of the limbs, pelvis, and vertebral column

INTRACARTILAGINOUS OSSIFICATION

At the start of ossification, the chondrocytes in the center of the cartilage model hypertrophy and their lacunae enlarge

Types of bone according to shape

Long bone
Short bone
Flat bone
Irregular bone
Sesamoid bone

Long bone

Tubular and consists of a body or shaft and two ends (proximal and distal epiphyses)

Long bone

confined to extremities

Short bone

Cuboidal

Short bone

confined to wrist and ankles

Flat bone

typified by the sternum, scapulate and bones of the skull

Irregular bone

includes the vertebrae, hip bones and bones of the skull that are NOT flat (coccyx, sacrum)

Sesamoid bone

Develop in tendons that rub bony surfaces

Sesamoid bone

found in the patella or knee cap

Flat Bone

Which type of bone contains the Sternum?

Irregular Bone

Which type of bone contains the Vertebra?

Long Bone

Which type of bone contains the Femur?

Sesamoid Bone

Which type of bone contains the Patella?

Lateral cuneiform
Intermediate cuneiform
Medial cuneiform

Give 3 examples of Short Bone

Periosteum

• Connective tissue that covers the external surfaces of the bone

Periosteum

• Consists of an outer layer (fibrous) and osteogenic layer (inner)

osteoprogenitor

• Osteogenic layer have ____ cells

Sharpey’s fibers

• Collagen fibers trapped within the bone matrix is called ___

Sharpey’s fibers

• serve to anchor the periosteum to the bone more firmly.

Endosteum

Lines all medullary marrow and vascular cavities of bones

Endosteum

Thinner than periosteum and often consists of single layer of osteoprogenitor cells

• Bone matrix (intercellular substance)
• Lamellae
• Lacunae
• Canaliculi
• Osteocyte

Composition, Microscopic structure and Architecture of Bone tissue

Spongy bone (cancellous)

Has numerous spaces visible to the naked eye

Spongy bone (cancellous)

More abundant in the body

Spongy bone (cancellous)

Accounts for 20-25% of body’s total skeletal mass

Compact bone(cortical, dense)

Accounts for 75-80% of body’s total skeletal mass

Compact bone(cortical, dense)

Outer casing appears as a solid mass

Compact bone

Which type of bone has the Haversian system/osteons?

Haversian system/ osteons

make up the bulk of compact bones

Haversian system/ osteons

consists of lamellae, lacunae and osteocytes that is arranged concentrically around vascular channels (Haversian canal/canal of Havers)

Haversian canals

connected by transverse channels called Volkmann’s canals

Volkmann’s canals

Haversian canals are connected by transverse channels called ____

Volkmann’s canals

contain blood vessels & nerves and are lined by endosteum

Compact bone

What type of bone contains the Interstitial lamellae?

Interstitial lamellae

found in between Haversian systems that are not arranged around a Haversian canal

Interstitial lamellae

remnants of Haversian systems

Compact bone

What type of bone contains the Circumferential lamellae

Circumferential lamellae

lamellae that encircle the whole bone or whole medullary cavity

Bone Matrix

composed of ground substance and extracellular fibers

• water

• inorganic minerals

• organic substances

Components of Ground substance

Inorganic minerals (Bone Matrix)

–  mainly calcium and phosphorus

Inorganic minerals (Bone Matrix)

include bicarbonate, citrate, magnesium, potassium and sodium

Organic substances

– proteoglycans

– non-collagenic proteins

– glycoproteins

Extracellular fibers

Mostly Type I collagen fibers

Extracellular fibers

They render the bone matrix acidophilic