Cartilage

Question 1

How do the two layers of the perichondrium differ?

Answer 1

External layer: made up of collagen, dense CT

Internal layer: rounded immature chondrogenic cells (chondroblasts–>chondrocytes)–NOT in articular cartilage

Resemble fibroblasts

Question 2

Where is the territorial matrix in relation to the chondrocyte? What about the inter territorial matrix?

Answer 2

Territorial: intercellular matrix close to chondrocyte (more basophilic)

Interterritorial: in between chondrocytes

Matrix as a whole is made up of chondronectin, collagen, elastic fibers, and proteoglycans

Question 3

explain the role of mesenchymal cells in chondrogenesis?

Answer 3

• give rise to cartilage through mitotic division, become hypercellular–>matrix will grow and separate chondrocytes –>they continue to multiply to form isogenous groups
• start producing ground substance of GAGs
• stem cells of bone and cartilage

Question 4

What is the name of the cluster of cells chondrocytes form within a lacuna?

Answer 4

Isogenous groups

Question 5

What is ground substance made up of and what are its functions?

Answer 5

• produced by chondrocytes
  1. produces CT like collagen and elastic fibers

2. Proteoglycans: pliability, strength and flexibility
3. Made up of GAG+protein=proteoglycans.

Give rise to different types of cartilage (embedded with collagen and elastic fibers)

Question 6

What type of cartilage uses articular cartilage?

How is this clinically relevant to osteoporosis and lameness i in horses?

Answer 6

Hyaline.

Does not have perichondrium. Articular cartilage detaches from bone and floats around.

Question 7

What are some examples of:

1. Elastic cartilage
2. Fibrocartilage
3. Hyaline cartilage

Answer 7

1. Elastic: Pinna of ear, larynx, epiglottis
2. Fibrocartilage: Intervertebral discs, symphysis (growth plate), insertion of tendons, menisci
3. Hyaline: Articular, Growth plates (physis), fetal axial & appendicular skeleton, nasal septum

Question 8

What types of CT make up the skeletal system and what are their functions?

Answer 8

1. cartilage: semi-rigid support at specific sites
2. bone: rigid protection and supporting framework of tissues
3. ligaments: stabilizes joints
4. joints: composite structures that unite bone; allow varying degrees of motion
5. tendons: strong flexible connections between muscles and bones

Question 9

Hyaline Cartilage

Answer 9

• most common type of cartilage
• characterized by small aggregation of chondrocytes embedded in ground substance matrix
• reinforced by Type II collagen

Question 10

What components make up the matrix of hyaline cartilage?

Answer 10

1. Chondroitin sulfate + protein make up proteoglycan
   - glycoproteins: chondronectin
   - Type II cartilage

Stains basophilic

Question 11

Elastic cartilage

Answer 11

• perichondrium
• chondroblasts and chondrocytes within lacunae
• elastic fibers: fibers bundle and branch allowing flexibility

Question 12

Fibrocartilage

Answer 12

In areas that need support and tensile strength; made up of rows of chondrocytes within lacunae and separated by bundles of fibrocartilage

• no perichondrium
• cartilage and dense CT (intermediate features)
• Type I collagen fibers

Question 13

Overview of cartilage

Answer 13

• avascular, semirigid
• absence of blood vessels, lymphatic vessels and nerves
• supports soft tissue, important for bone growth
• cells embedded in ground substance with CT fibers

Question 14

Mature chondrocytes are characterized by:

Answer 14

Small nuclei with dispersed chromatin, basophilic granular cytoplasm, well developed rough ER

-rich in glycogen and also contain lipids

Question 15

What’s the difference between appositional growth and interstitial growth?

Answer 15

Interstitial: from within the cartilage

Apositional: growth at the periphery; like in growth plates