General Histology Lecture 15: Cartilage

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Questions and Answers

What type of tissue is cartilage classified as?

Connective tissue (correct)

Nervous tissue

Muscle tissue

Epithelial tissue

Which of the following types of cartilage does not have a perichondrium?

Hyaline cartilage

All types of cartilage have a perichondrium

Elastic cartilage

Fibrocartilage (correct)

What is the primary function of cartilage in the joints?

To facilitate smooth movement of bones (correct)

To provide nutrients to the bones

To store fat and energy

To produce synovial fluid

How do chondrocytes receive nutrients?

By diffusion from surrounding connective tissue Signup and view all the answers

What major component is found in the extracellular matrix of cartilage?

Proteoglycans and GAGs Signup and view all the answers

Which of the following statements is true regarding the perichondrium?

It nourishes cartilage through direct blood supply Signup and view all the answers

Where can hyaline cartilage be typically found in the body?

In the respiratory tract Signup and view all the answers

What role does cartilage play in the development of long bones?

It mediates growth before and after birth Signup and view all the answers

What substance primarily contributes to the semi-rigid consistency of cartilage?

Water bound to hyaluronan and GAGs Signup and view all the answers

Which type of matrix contains abundant proteoglycans and less collagen surrounding chondrocytes?

Territorial matrix Signup and view all the answers

Aggrecan is primarily composed of which type of side chains?

Chondroitin sulfate and keratan sulfate Signup and view all the answers

What is the primary function of chondronectin in cartilage matrix?

To mediate the adherence of chondrocytes to the ECM Signup and view all the answers

Which of the following is NOT a component of the cartilage matrix?

Fibroblasts Signup and view all the answers

The structure that binds non-covalently to hundreds of proteoglycans in cartilage is known as what?

Hyaluronic acid Signup and view all the answers

Which type of fibers are predominantly found in the cartilage matrix?

Type II collagen fibrils Signup and view all the answers

What is the role of glycosaminoglycans (GAGs) in the cartilage matrix?

Binding water and enabling resistance to compression Signup and view all the answers

What distinguishes elastic cartilage from hyaline cartilage?

Abundant network of elastic fibers Signup and view all the answers

Which staining method is used to demonstrate the elastic fibers in elastic cartilage?

Orcein stain Signup and view all the answers

In which of the following locations would you typically find elastic cartilage?

Auricles of the ear Signup and view all the answers

What characterizes the structure of fibrocartilage?

Dispersed chondrocytes among type I collagen fibers Signup and view all the answers

Which component is NOT a characteristic of elastic cartilage?

Dense regular connective tissue Signup and view all the answers

What role do the type I collagen fibers play in fibrocartilage?

Contributing to tensile strength Signup and view all the answers

Which tissue type lacks a distinct surrounding perichondrium?

Fibrocartilage Signup and view all the answers

What functional characteristic is attributed to both elastic cartilage and hyaline cartilage?

Ability to resist compressive forces Signup and view all the answers

What is the function of the outer fibrous layer of the perichondrium?

It facilitates nutrient diffusion to the cartilage matrix. Signup and view all the answers

Which cell type is derived from chondrogenic cells and actively synthesizes cartilage matrix?

Chondroblasts Signup and view all the answers

What characterizes chondrocytes within the cartilage matrix?

They are trapped in lacunae after differentiation. Signup and view all the answers

In which cellular arrangement do chondrocytes often appear due to mitotic divisions?

Isogenous groups Signup and view all the answers

What structural feature is observed in chondrocytes during routine histological preparation?

They may shrink and appear irregular. Signup and view all the answers

What types of fibers are primarily contained in the outer layer of the perichondrium?

Collagen type I fibers Signup and view all the answers

What type of cellular structures do chondrocytes typically exhibit in their cytoplasm?

Mitochondria and RER Signup and view all the answers

Where are chondrogenic cells primarily located within the perichondrium?

In the inner cellular layer Signup and view all the answers

What are the main characteristics of chondrocytes in fibrocartilage?

They are dispersed among collagen fibers in various arrangements. Signup and view all the answers

What distinguishes fibrocartilage from other types of cartilage?

It has no surrounding perichondrium. Signup and view all the answers

What initiates appositional growth of cartilage?

Differentiation of mesenchymal stem cells in the perichondrium. Signup and view all the answers

Which process describes the growth that occurs within an existing cartilage mass?

Interstitial growth. Signup and view all the answers

How does the lack of perichondrium in fibrocartilage affect its growth?

It restricts the growth to interstitial processes only. Signup and view all the answers

What type of collagen is predominantly produced by chondrocytes in fibrocartilage?

Type II collagen. Signup and view all the answers

What is the role of fibroblasts in the structure of fibrocartilage?

They produce matrix components and provide tensile strength. Signup and view all the answers

What is the mechanism of cartilage formation from mesenchyme called?

Chondrogenesis. Signup and view all the answers

Study Notes

General Features of Cartilage

Cartilage is a specialized connective tissue providing support and weight-bearing capabilities.
It is avascular; nutrients diffuse from surrounding perichondrium.
Composed of chondrocytes within an extracellular matrix enriched with glycosaminoglycans (GAGs) and proteoglycans.
ECM consists of type II collagen fibrils and occasionally elastic fibers, allowing resistance to mechanical stress.
Chondrocytes reside in lacunae within the matrix.

Functions of Cartilage

Supports soft tissues, e.g., in the respiratory tract (nose, larynx, trachea).
Facilitates smooth movement of bones at joints.
Mediates growth and development of long bones before and after birth.

Perichondrium

Definition: A dense irregular connective tissue sheath surrounding cartilage, except in articular and fibrocartilage.
Contains blood supply for cartilage nutrition and neural elements.
Has two layers:
- Outer fibrous layer with collagen type I fibers, fibroblasts, and blood vessels.
- Inner cellular layer with chondrogenic cells that can differentiate into chondroblasts for cartilage growth and maintenance.

Cartilage Cells

Chondrogenic Cells: Located in the inner layer of perichondrium, they differentiate into chondroblasts.
Chondroblasts: Young chondrocytes that secrete cartilage matrix, exhibiting basophilic cytoplasm due to abundant rough endoplasmic reticulum (RER).
Chondrocytes: Mature cells located in lacunae, capable of division and often organized in isogenous groups from mitotic divisions.

Cartilage Matrix

Composed of fibers (mainly type II collagen, some type I or elastic) and ground substances (GAGs, proteoglycans).
The structure allows cartilage to withstand compression and return to original shape due to bound water.
Aggrecan: Predominant proteoglycan in hyaline cartilage, linked to hyaluronic acid, imparting resilience.
Territorial Matrix: Surrounds chondrocytes, rich in proteoglycans and less collagen, appearing basophilic in staining.
Interterritorial Matrix: Fills the remaining space, surrounding the territorial matrix.

Types of Cartilage

Elastic Cartilage: Contains elastic fibers alongside type II collagen, providing both stiffness and elasticity. Found in the ear, epiglottis, and Eustachian tube.
Fibrocartilage: A blend of dense connective tissue and hyaline cartilage, containing dispersed chondrocytes and aligned collagen bundles. Found in the pubic symphysis and intervertebral discs. Lacks a surrounding perichondrium, conferring tensile strength.

Cartilage Development and Growth

Cartilage arises from mesenchyme through chondrogenesis, where mesenchymal cells differentiate into chondroblasts.
Appositional Growth: New cartilage forms at the surface from chondrogenic cells in the perichondrium; most cartilage growth occurs this way.
Interstitial Growth: Increases cartilage mass from within via chondrocyte division; prevalent in fibrocartilage and epiphyseal plates of long bones.

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Description

This quiz covers the essential features and histological types of cartilage based on Lecture 15 of the General Histology course. Participants will be tested on their ability to recognize, list, and demonstrate the main characteristics of various cartilage types. A good grasp of cartilage locations within the body will also be evaluated.