عملي Oral

CARTILAGE and bonem.sc.sarah ahmed

انسجة عملي / د . سارة ( م 4 - 5) ثاني اسنان موصل 9/ 12 / 2015

PERICHONDRIUM

is a layer of dense irregular connective tissue that surrounds the cartilage. No blood vessels or nerves It consists of two separate layers: an outer fibrous layer and inner chondrogenic layer. Present in most of the hyaline & elastic cartilage Absent in fibrocartilage
Fibrous layer
Cellular layer

CHONDROBLAST

cells that develop from the mesenchymal and form cartilage Progenitor of chondrocytes Lines border between perichondrium and matrix

CHONDROCYTE

Mature cartilage cell Reside in a space called the lacuna Isogenous cell group

TYPES OF CARTILAGE

HYALINE ELASTIC FIBROUS

Figure 4.8g Connective tissues.

(g) Cartilage: hyaline
Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae.
Function: Supports and reinforces; has resilient cushioning properties; resists compressive stress.
Location: Forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx.
Photomicrograph: Hyaline cartilage from the trachea (750x).
Costal cartilages
Chondrocyte in lacuna
Matrix

HYALINE CARTILAGE

Figure 4.8h Connective tissues.
(h) Cartilage: elastic
Description: Similar to hyaline cartilage, but more elastic fibers in matrix.
Function: Maintains the shape of a structure while allowing great flexibility.
Location: Supports the external ear (pinna); epiglottis.
Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (800x).
Chondrocyte in lacuna
Matrix

Figure 4.8i Connective tissues.

(i) Cartilage: fibrocartilage
Description: Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate.
Function: Tensile strength with the ability to absorb compressive shock.
Location: Intervertebral discs; pubic symphysis; discs of knee joint.
Photomicrograph: Fibrocartilage of an intervertebral disc (125x). Special staining produced the blue color seen.
Intervertebral discs
Chondrocytes in lacunae
Collagen fiber

: fibrocartilage

Histology of Compact Bone
Osteon – the structural unit of compact boneLamellae – matrix tubes composed of collagen and crystals of bone saltsCentral canal - (Haversian canal) canal containing blood vessels and nerves

Histology of Compact Bone

Lacunae - cavities in bone containing osteocytesCanaliculi - hairlike canals that connect lacunae to each other and the central canalPerforating canal (Volkmann’s) – channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to the central canal (interconnecting the Haversian canals with each other and the periosteum). )


Cells in Bone
Osteoprogenitor cells – precursors to osteoblastsOsteocytes - mature bone cells between lamellaeOsteoclasts - bone-destroying cells, break down bone matrix for remodeling and release of calciumOsteoblasts - bone-forming cellsResponsible for osteogenesis (new bone)

The Structure of Spongy Bone

No osteons Lamellae as trabeculae plates of bone Branching network of bony tissue Strong in many directions Red marrow (blood forming) spaces

Short, Irregular, and Flat Bones

Plates of periosteum- covered compact bone on the outside with endosteum-covered spongy bone, on the inside Have no diaphysis or epiphyses Contain bone marrow between the trabeculae