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Questions and Answers
What is the primary function of cartilage?
Which type of cartilage is characterized by a perichondrium?
What is the main characteristic of cartilage tissue?
Which component of hyaline cartilage does NOT contain blood vessels?
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What type of fibers are abundant in the perichondrium of hyaline cartilage?
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At which location can hyaline cartilage NOT be found?
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What is the role of chondroblasts in cartilage?
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What distinguishes white fibrocartilage from other types of cartilage?
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What type of collagen fibers are primarily found in the matrix described?
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In which location would you find the type of cartilage that exhibits great strength and flexibility?
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What is the primary result of interstitial growth in cartilage?
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Which of the following hormones or factors significantly influences cartilage histogenesis?
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What limits the repair ability of cartilage after injury?
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What is a characteristic feature of osteoarthritis?
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Which process occurs at the periphery of cartilage and involves the differentiation of chondrogenic cells?
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What happens to hyaline cartilage as chondrocytes undergo hypertrophy and die?
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What is one of the primary functions of the perichondrium?
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Which type of cells are responsible for producing the extracellular matrix of cartilage?
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Where are chondrocytes primarily located?
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What characterizes the matrix of hyaline cartilage?
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How does the extracellular matrix of yellow elastic cartilage differ from that of hyaline cartilage?
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Which statement about chondrocytes is correct?
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What is a distinguishing feature of white fibrocartilage compared to other types of cartilage?
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What role does alkaline phosphatase play in older chondrocytes?
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Study Notes
Cartilage Histology
- Cartilage is a specialized connective tissue with a rubbery, rigid, and flexible matrix, distinctive cells, and a unique fiber population.
- Cartilage develops from mesenchyme.
- Unlike other connective tissues, cartilage lacks blood vessels, nerves, and lymphatics, making it susceptible to pressure and relying on diffusion for nutrients.
- Cartilage's primary functions include supporting soft tissues and assisting in the development and growth of long bones.
Cartilage Classification
- Cartilage is categorized into three types based on fiber abundance and type within the ground substance:
- Hyaline cartilage
- Elastic cartilage
- Fibrocartilage
Hyaline Cartilage
- The most common type of cartilage.
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Perichondrium: A connective tissue membrane surrounding hyaline cartilage except in joint cavities. The perichondrium has two layers:
- Outer fibrous layer: Dense connective tissue rich in type I collagen fibers, fibroblasts, and a few blood vessels.
- Inner vascular and cellular layer (chondrogenic layer): Contains chondroblasts, responsible for new cartilage formation.
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Cells:
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Chondroblasts:
- Immature cartilage cells originating from undifferentiated mesenchymal cells.
- Found in the inner chondrogenic layer of the perichondrium, arranged singly and parallel to the surface.
- They synthesize the specialized extracellular matrix of cartilage.
- As chondroblasts mature, they become enclosed within lacunae, transforming into chondrocytes.
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Chondrocytes:
- Mature cartilage cells found within lacunae.
- Superficial chondrocytes are small, flat, and aligned parallel to the surface.
- Deep chondrocytes (mature or old) are larger, rounded, oval, or triangular and arranged perpendicular to the surface.
- Chondrocytes can divide once or twice within lacunae, forming cell nests. Mature chondrocytes lack the ability to divide.
- Chondrocytes synthesize and secrete the extracellular matrix.
- Old chondrocytes secrete alkaline phosphatase.
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Chondroblasts:
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Matrix:
- Appears homogeneous and basophilic under the light microscope.
- Composed of a complex mixture of glycosaminoglycans (hyaluronic acid and chondroitin sulfate) and structural glycoproteins (chondronectin).
- The basophilia is attributed to the presence of glycosaminoglycans.
- Contains type II collagen and elastic fibers, but they are too thin to be visible with a light microscope.
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Sites of hyaline cartilage:
- Costal cartilage
- Long bones of the fetal skeleton
- Articular cartilage
- Trachea and bronchi
Elastic Cartilage
- Resembles hyaline cartilage, with a perichondrium present.
- However, the matrix contains abundant yellow elastic fibers.
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Sites:
- Ear pinna
- External auditory meatus
- Eustachian tube
- Epiglottis
Fibrocartilage
- Lacks a perichondrium (intra-articular).
- The matrix contains abundant parallel collagen fibers type I, separated by rows of chondrocytes.
- Provides significant strength and flexibility.
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Sites:
- Symphysis pubis
- Intervertebral discs
- Interarticular cartilages
Cartilage Histogenesis
- Cartilage growth is influenced by hormones and vitamins.
- Occurs through two processes:
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Interstitial growth: Cell division of pre-existing chondrocytes.
- Occurs primarily during the early stages of cartilage formation and in articular cartilage.
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Appositional growth: Differentiation of chondrogenic cells in the perichondrium.
- Results in the formation of chondroblasts and new chondrocytes, which secrete new cartilage matrix at the periphery.
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Interstitial growth: Cell division of pre-existing chondrocytes.
Cartilage Degeneration
- Occurs when chondrocytes undergo hypertrophy and die, and the matrix becomes calcified.
- A common part of endochondral bone formation.
Cartilage Repair
- Cartilage has a limited ability to repair after injury due to:
- Avascularity
- Immobility of chondrocytes
- Limited ability of mature chondrocytes to proliferate.
- Extensive damage results in fibrous tissue repair instead of cartilage regeneration.
Medical Application: Osteoarthritis
- A degenerative joint disease commonly characterized by chronic joint pain and varying degrees of joint deformity.
- Involves the destruction of articular cartilage.
- Characterized by a reduction in proteoglycan content, leading to decreased intercellular water content within the cartilage matrix.
- Chondrocytes contribute to osteoarthritis pathology.
- They produce interleukin-1 (IL-1) and tumor necrosis factor α (TNF-α), stimulating the production of metalloproteinases.
- This process simultaneously inhibits the synthesis of type II collagen and proteoglycans by chondrocytes.
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Description
This quiz delves into the histology and classification of cartilage, highlighting its unique characteristics and types. Explore the features of hyaline, elastic, and fibrocartilage, along with their roles in the human body. Perfect for students studying connective tissues.
